Dianas, Holgas, Wocas, Lubitels (yeah, them too!), you know them, 100% plastic, plastic or cheap glass for lenses, light leaks, heavy vignetting. Let's get plastic fantasic out at Klyde Warren!
If you've never shot with a toy camera, but are interested come out, everyone who shoots with these cameras always has an extra one or two laying around that you can borrow. Or if you want to jump in with both feet, Diana's and Holga's can be found very inexpensive on eBay, Arlington Camera also used to carry them because UT-Arlington's photo program used them as part of their Intermediate Photo classes, they start at $35
You can also find them new online at Freestyle Photo, would recommend staying away from Lomography as their prices tend to run a bit on the high end.