I have bought a bunch of fans from
www.allelectronics.com and
www.hosfeltelectronics.com
There are a ton of them... many @ $2-3 each. Look for the thin ones... watch the specs. You don't want the fat boys. I like the 40mm fans for the esc. If the motor is next to the esc you can run a bigger fan and get both some air.
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+