Try some place like Menards. Do you have them around there?
sometimes its hard to find the black ones, which don't show up too much in water.

Walmart sells plastic ones in their home office supplies department. They're not as sturdy as real milk crates, but come in several sizes.

Thanks for the replies, but actually I don't think I worded that right -- what I'm looking for are the ones that look like plastic pallets.

I'd probably just walk around a big hardware store in various departments and maybe find something that's meant for a different use, but would work for you.

I don't think I have ever seen a plastic pallet. Where have you seen them? Can you ask there about where they were purchased?

nancym,

Would one of those "trays" that bread is delivered in work? They are about, oh, 3X3 or so with a lattice-type of base. Don't know if I'm wording this right, but that's what came to mind when I read your post. The link below has pictures of what I'm thinking of.
Anne

Here is a link that might be useful: Flexcon Plastic Containers

Anne, the bakery pallet trays are more what I'm looking for. Thanks for the link.

Sleepless, my dad had some. He used them for drying potatoes and onions on. Unfortunately, he passed away a few years ago, so I don't know where he got them. They look a lot like those blue bread trays, though. I have a few of them, but I don't want to cut those particular ones down to size. Sentimental reasons, I guess.

I'm also considering egg crate, which should be fairly easy to cut to size.

Thanks, all.

In the areas where hardware stores have their drop-ceiling materials, they should have a plastic grate that fits underneath fluorescent light fixtures. It's about 2' x 4', with 1/2" squares and maybe 3/8" thick and comes in white and "chrome" and is easily cut to shape with plain old wire cutters - it's not necessarily cheap ($14 or $15 a piece), but maybe this'll work for ya?

I use this grating in my biofalls as a support for the filter mats and as a fence to keep the hyacinth constrained - worked great!

You might also look at nursery/landscape Internet sites. Their shelving is plastic, but the openings might be too big.....but they might come with smaller openings.

If you are looking for filter supports check these out at:

http://www.aquaticeco.com/subcategories/3100/Filter-Grating-1-1-4-Thick/floor%20panel/0

Or go to Aquatic Eco Systems and search for filter grating.

go behind or to a local party store and get some black coke shells that are used for carry pop