My husband just found this sand/water play table for our daughter at a consignment shop: http://www.amazon.com/gp/product/B0000WXGL8?ie=UTF8&tag=likmershi-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=B0000WXGL8
It's plastic, but not overboard on the colors.

Take a look at this one:

http://www.wooddesigns.org/product_details.asp?modelNumber=11810

That wooden one is nice, but almost $400?!?
What about finding a used coffee/small table and cutting out a section in the middle to fit a plastic bin?

There was an ikea hack on here a couple months ago. Not sure how it would work outside but it should be pretty easy to put together. http://www.ohdeedoh.com/ohdeedoh/how-to/sensory-table-how-to-106693

I found a $10 kitchen sink with faucet on craigslist and my hubby built a very basic small frame for it. We set it up outside and hooked it up to the hose. Perfect! Ours has two sides; I intended to use one for sand, but the water is just as much fun. No need to have a drain, just let it go into the garden.

Here's a picture:
http://saturatedroots.blogspot.com/2010/01/where-did-you-go-december.html

Saturatedroots, love it.

If you really want use out of a sensory table, then forget how it looks and go for sturdiness and ease of cleaning. Seriously. Find something you can put water, shaving cream, ooblick, sand, beans, jello, whatever on, and just have fun with it.

The tan colored Step2 sand-water tables aren't too gaudy. They're plastic, but the colors are neutral enough. The little bridges on the table are also really cute. I don't typically go for the plastic stuff, but for outdoor toys there are benefits.

For something that gets really messy and is played with outdoors (I am way too anal to have an indoor sand or water table at our place) I say, just go with the plastic. It's easily hosed down and if it's left out in the rain you won't worry about it.

Here's a great diy solution.

http://www.ericsprojects.com/?page_id=88