I got mine from Boomtown Hobbies in Oregon http://www.boomtownhobbies.com/

But I think the mCX might use different motors. If I were you, I'd just replace the bad motor first with the manufacturer's replacement. I wouldn't think it would cost more than $10. The reason I went for the Xtremes was that my LHS didn't have a replacement motor and I was planning on Xtremes for some time already.

If it turns out that the motor was at fault, you can then plan any "upgrades" separately from your current problem.

Since the mCX is such a tiny heli, Iwouldn't put too much money in it unless that's what floats your boat. Personally I'm trying to wean myself from any more upgrades as I plan to get a bigger heli once I've convinced myself I can handle it.

Mack