I am sitting behind same problem try to find good and cheap UBEC's
http://home.comcast.net/~truerc/esc/escNmotor.htm
If you scroll down yow will see three UBEC's with price aup to $15
Wich one to choose?
3A Ultra BEC Board -exactly same Bec as in ebay link -$12
3A Dynam Ultra BEC Board -$15
3A ASSAN Ultra BEC Board -$10
which one to choose?