Wal-Mart, Home depot, lowes, etc. have whole sections devoted to just this material. But they are more commonly called trash cans. I'm a fan of rubber maid myself :thumbsup
If you can find a plastic supplier locally it will be much cheaper than even ordering online. Local places will often have sheets of scrap and sell them for cheap since they will be getting rid of waste and not having to cut anything. I was able to get a 4'x4' sheet in Tampa, FL for $13
Wal-Mart, Home depot, lowes, etc. have whole sections devoted to just this material. But they are more commonly called trash cans. I'm a fan of rubber maid myself :thumbsup
Try the dollar stores too. The cans are smaller but sometimes cheaper. I got some off brand one at walmart for 9.99 and traded it to my dad for his beat up one lol. I'm using one for my Fallout robobrain project.