ok for the Rex a must have is a brushless system. The rex line (as well as clones) are a bit under powered for their size, so get a ALIGN 420LF they're not THAT expensive (actually pretty cheap) and with a 25A-35A esc you'll be able to tackle just about any type of flying, which is excluding crashes of course. The rex is the best 3D micro because of it's relativly cheap parts for replacements. A pair of blades is usually 10-20 dollars which is the best anywhere. if you go the TRex route you MUST get the brushless system as well as a pair of abs blades and a pair of woodies. Abs blades are near invencible and will probably out last your helicopter. as for the woodies the're for when you get good so you can do 3D manuveres. My favorite place to go for the Trex parts (also the cheapest with the fastest shipping as all their stock is IN the us so you should get your order in 3-4 days