allelectronics.com has some cheap 1v 550-600 size motors for about $3 each. This one is a normal Johnson type...
http://www.allelectronics.com/cgi-bi...3-24_VDC_.html
and there are a couple others too like this big motor with an oddball shaft on it
http://www.allelectronics.com/cgi-bi...DC_MOTOR_.html
Ebay is another good place to look of course
Jammin CRT MM/Neu 1515 1700kv
Losi 8IGHT MM/Neu 1512 1900kv
Kyosho 777
T4 MM 5700
B4 LRP
XX4 MM 7700
old losi xxcr, MM4600 4s lipo 70mph+