If you are adventuresome, you might try goodluckbuy, or futurlec. they are bot Chinese outfits and take forever to get your parts to you. They get crappy reviews because of this, but they have lots of stuff on the cheap, and I have not had any problem with them. I got a cheap Arduino due clone from goodluckbuy that was a better board than the true one. it was only around $18 and the shipping is free.
Take a look. there is a lot of stuff that's lots of fun.