Just before I bought mine, I asked what spares I should grab. I was told by many that I might not need any at all. For the most part, that ended up being true. The only thing I ever broke, and on a regular basis, is the landing skid, which I've now modded to never break again
I did break a flybar but that was my own fault and was inevitable considering what I was doing with the heli at the time.
I did buy the CF Tail Boom right from the get go (you might develop a tail vibration with it on, but that's an entire discussion in itself). One of its benefits is it will keep your motors cooler.