Archer_

I'm looking to get into the world of GBBR's by picking up a second hand one from here on the forum. My only worry is with something breaking and not being able to get hold of backup parts. So far, the only one that seems to have a plethora of spares online is the TM MWS, however that's obviously right up there when it comes to budget. So, question to anyone a little more adept in the world of GBB, where do you buy from? Should I be worried about my gun breaking? And what GBB options are the best for maintaining? For clarity, I've been looking mostly at the TM MWS, GHK M4s or the TM MP7. Thanks in advance!