Does anyone know a place where I can find it? Two or three years ago our team found some, and we forgot where it was that we had found it.
Thanks in advance…
Give this a try… 
Try Yarde Metals, or your local metal supplier. Yarde has a drop zone page where you can buy less than full sheets and lengths. These are cut offs so you can save some money.
McMaster - Carr . Go there. Go there now.
http://www.metalsupermarkets.com/
they cut everything to size you need (no minimums), and they normally are willing to negotiate on price (especially if you have cash with you when you go there)…we recieved a significant discount on our aluminum there…
Here’s the odd idea for you…in our area we have a tent company who will give us their spare alluminum tubing. We’ve got some very nice stuff…and they’ve willingly donated more than we need. So if you have a tent company, which I’m highly doubting anyone will have in their area, check them out.