No suggestions, but I've noticed that stuff like this at Target is really seasonal. Keep looking. You may see some fun colors when back to school rolls around.

Yeah, Target usually brings them back for Back to College.

These Strapping Bins by Land of Nod are $11 each and they fit perfectly in our expedit. Not so snug that the kid can't take the basket out by himself, but no gaping holes either.

http://www.landofnod.com/strapping-cube-bin/f670

This may or may not be appropriaate for you, but may help someone. We have the Martha Stewart fabric bins/drawers in our Ikea Expedit. They do not completely fill the void and (are slightly short)...check the dimensions. The colors are what I would describe as earthy/vegetable-like, not crayon-like, but are still "bright enough". They are $7 each at Home Depot (sorry for the long link):

http://www.homedepot.com/webapp/catalog/servlet/Search?storeId=10051&langId=-1&catalogId=10053&keyword=martha+stewart%20fabric%20drawer&Ns=None&Ntpr=1&Ntpc=1&selectedCatgry=Search+All

As someone mentioned above, Home Depot has them but also Lowes, Osh, and sometimes at the discount stores. In CA, you'll find them at times at Marshalls, Ross and Kohles. The target in Richmond, CA still has them in fun colors. Why not try ordering them on-line from Target?
Cute set up btw...Good Luck.

Try putting Itso in ebay.

Ikea themselves offers all sorts of drawers/bins that fit into the expedit.
Below are the names and a couple of them come in a variety of colours:
- Dröna
- Branäs
- Bladis
- Lekman
- Kvittra
- Knipsa
- Kottebo

It's worth checking them out and a few of them you could even spray paint to match your color scheme :)

I don't have a solution, but I'd like to post a similar complaint about Land of Nod. 4 years ago when we got the expedit for the playroom, I bought the canvas bins from land of nod because I loved the colors. It was as if they were made for the expedit. Fit perfectly. No gaps. Fast forward two years and we get another expedit. I order the same bins from Land of Nod and they are now insanely smaller - seemingly to fit their version of the bookcase!

There. It feels good to vent. :) As a result, I've been searching for similar/coordinating colors so I don't have to redo everything.

I have the same set of shelves and picked up a bunch of the DRONA Storage Boxes @ Ikea. Cheap and currently come in a few fun colors (green & pink online- might have more in store) http://www.ikea.com/us/en/catalog/products/30219281/#/10221591

Am I missing something? Surely the first place to look is Ikea itself, maker of the shelf units?

I bought some on Amazon when my Target didn't have them.

Target's stock on this product has been really low for a while due to a glitch on the manufacturing side of things at Itso. Maybe because of high demand that they just couldn't keep up? I don't know if there's a resolution date yet, but you'll probably see the same few basic colors for a few months still.

Container Store offers several options.

thanks for the help, everyone. off to check out your suggestions. someone on etsy could make a fortune selling cute 13"x13"x13" boxes—if only i could sew!!

We have bins from World Market in ours. Or Pier One - can never remember!

Milk crates are 9.99 at The Container Store if you'd like to complete the collection
http://www.containerstore.com/shop?productId=10000531&N=&Ns=p_sort_default%7C0&Ntt=crate

I bought adhesion spray primer and some spray paint in primary colors and painted the baskets sold at ikea.

I just checked Target and the Itso Large Polka Dot Fabric Bin is back in stock:
Itso Large Polka Dot Fabric Bin

It's on sale for $8.99.

if you are handy (or know someone who is) something like this could be easily sized to fit and painted any number of colors - lowe's sells paint samples at $3 each to finish them up.

http://ana-white.com/2013/01/plans/chalkboard-produce-crate