Mgawa- I'm not really sure about ducted fan performance. All my experience thus far has been with lipo batteries and brushless motors, hooked to external propellers.
I'm sure the guys over at
www.rcgroups.com have some threads on ducted fans and which combination works best. For what it's worth, I use
www.hobbycity.com for all my RC parts. Gotta love cheap motors and batteries!