Dwellstudio (if you want to drop serious money). And have you checked Land of Nod? Or Bananafish/Migi?

If you've seen those (which you probably have), why not buy some Amy Butler-ish fabric and make the bedding custom?

I was going to say Dwellstudio (or their Target line) too. Expensive, but pretty good quality. I used the same crib sheets for both daughters and they've held up well.

I LOVE this bedding. Also, from Dwell :) If I could afford the girl cutout doll bedding I would get that.

http://www.target.com/DwellStudio-Target-Tulip-Bedding-Collection/dp/B002SDDDUG/ref=sr_1_21?ie=UTF8&searchView=grid5&keywords=dwell&fromGsearch=true&sr=1-21&qid=1279734804&rh=subjectbin%3A1038590&searchRank=target104545&id=DwellStudio%20Target%20Tulip%20Bedding%20Collection&node=1038576%7C1287991011&searchSize=30&searchPage=2&searchNodeID=1038576%7C1287991011&searchBinNameList=subjectbin%2Cprice%2Ctarget_com_primary_color-bin%2Ctarget_com_size-bin%2Ctarget_com_brand-bin&frombrowse=0

You could also check out the Pottery Barn "wishes" bedding items in pink. No longer available at PB, but you can find them new on ebay. pink/white/grey colors and fairly simple/not too busy. good luck!

Another idea is to spring for some of the fun Dwellstudio fitted sheets, then fill in the rest of the bedding collection with some solid-color selections from Carousel Designs--they offer swatches so you could see the colors before ordering. This same approach could work if you go the custom route--have a bumper or crib skirt made in a fabric of your choice, then fill in the rest with solids.
Solid Baby Bedding:
http://www.babybedding.com/solid-colors-crib-bedding
DwellStudio crib sheets:
http://www.dwellstudio.com/designer-baby-boutique/nursery-bedding/crib-fitted-sheets.html

Depending on your budget...Etsy is a great place to look!!

I second the idea of having crib bedding custom made in some of Amy Butler's fabrics. I am just finishing up my daughters' room and we did gray walls with fabrics from Amy Butler's lotus line and I love how it turned out. If you are looking for a twin duvet cover for now or down the road, West Elm has some beautiful light gray and ivory patterned bedding right now.

Javis Davis does custom bedding. They have some wonderful fabrics to choose from: http://www.javisdavis.com/collections/bothfabrics.html Pricey but beautiful.

Annette Tatum Home (http://annettetatum.com/) does beautiful bedding in your color range if it works within your budget. Three piece sets generally run $394. The Brocade Peony set could be really beautiful in your room. baby coco (http://www.babycoco.com/contact.html) in Austin, TX is offering 15% off special order crib bedding through July 31st. If you are not in Texas, there is no tax. Shipping is free.

Here's a very mod graphic pink, grey, black and white set.

JCPenney has a solid pink set with quilted dots that may work.

I like this Flow bedding, but it is definitely pink and brown, not pink and grey.

One more -- Cotton Tale Poppy bedding?

Keep in mind that all you really need for bedding are sheets and a crib skirt, if you want one. Dwell has a crib sheet in dove gray with a squares pattern, and I wouldn't be surprised if you could find a plain gray or silver crib sheet. There are certainly a zillion pink fitted crib sheets out there. For the crib skirt, find a fabric you like, such as one of the Amy Butlers suggested above, and make it yourself or have one made, they're very simple. Match it to the curtains, or to a glider cushion.

Oooh, you can also purchase get individual components of this Glenna Jean Kirby bedding, if you don't mind a few additional colors.

Pink gray and white but a bit expensive:

http://www.poshtots.com/Bedding/Baby-Bedding/Girls-Baby-Bedding/Sophia-Baby-Bedding/15/221/1329/20098/PoshProductDetail.aspx

Just gray bedding:

http://www.roomandboard.com/rnb/product/detail.do?productGroup=19594&catalog=room&category=rm_bedrooms&subcategory=kid_nursery

Pink and gray sheet:

http://www.designpublic.com/shop/q-collection-junior/14160

Here is a simple linen pink, grey and white set from roy g baby.

http://www.roygbaby.com/collections/pure-linen-tri-colored-crib-sets/products/grey-scale-rosy-pink-white-crib-set-2

I immediately thought of the DesignPublic link from above.

Another:

Very simple dots: http://www.garnethill.com/dot-to-dot-percale-bedding/kids-rooms/bedding/crib-bedding/117602

I'd get a Matteo Home crib skirt in cloud (a dark grey), either in Folk,

http://www.laylagrayce.com/Products/Matteo-Baby-Bedding-Folk-Crib-Skirt__MAT108.aspx

Or Linen Gathered

http://www.laylagrayce.com/Products/Matteo-Baby-Bedding-Vintage-Linen-Gathered-Crib-Skirt__MAT131.aspx

Or Linen Flat

http://www.laylagrayce.com/Products/Matteo-Baby-Bedding-Vintage-Linen-Flat-Crib-Skirt__MAT126.aspx

(white or a neutral linen would also look amazing)

And an assortment of crib sheets, both cotton and linen.

http://www.laylagrayce.com/Products/Matteo-Baby-Bedding-Vintage-Linen-Crib-Sheet__MAT127.aspx

http://www.laylagrayce.com/Products/Matteo-Baby-Bedding-Cotton-Crib-Sheet__MAT130.aspx

Very chic, very simple.

I'm using similar colors in my baby girl's nursery. I had a quilt and bedskirt made by a woman from Etsy. I wanted a whole cloth quilt-- maybe these fabrics will give you some inspiration. Here's the link to the etsy page. The woman's name is tanneicasey. She is amazing and incredibly affordable. For a custom quilt and bedskirt, I paid $110 (that included all fabrics). I'm sure she'd do a bumper for pretty cheap if you wanted it. I highly recommend her!

http://www.etsy.com/transaction/30069245

Good luck and congrats!!

Actually, you might like all of the fabrics in the Alexander Henry Lorenza Nude line. It has all the colors you described. I just used the stripe-y looking one in the quilt and bedskirt.

http://www.hawthornethreads.com/fabric/bundle/lorenza_in_nude

have you looked at serena and lily? good luck:)

Love these guys around the world collection
http://www.kukunest.com/index.php

i had my daughter's crib set made by polkatotdesigns.com. they do amazing work and have an good selection of pink/gray fabric to work with. you can totally customize your set however you want it, add a monogram, type of bed skirt, etc. i live across the country from their shop and was so happy with their customer service, craftsmanship and turnaround time!

I can't tell if it's pink or more purple-ish(on sale at the moment):
http://www.laylagrayce.com/Products/Nurseryworks-Crib-Bedding-Set-Dottie-Lavendash---Final-Sale__NW34.aspx

Alexander Henry Thea Pink is kind of pretty fabric: http://www.sewmamasew.com/store/ecom-prodshow/AHTHEAPK.html

Modern Nursery have a good selection of modern bedding:
http://www.modernnursery.com/items.cfm/pcid/9/cid/37/all/1

Here they have lot's of bedding in different styles and patterns:
http://www.rosenberryrooms.com/gicrbe.html

Another vote for Serena and Lily. Also: I totally agree, you only need the sheet and a skirt (if you want one), as blankets and bumpers are discouraged because of SIDS.

I wish I had listened to my mother and got knit sheets; the regular cotton ones shrink in the wash and are harder to put on. But I've never seen jersey prints...maybe if you do Etsy you can work that out...