Another thing is they shoot'm and don't clean the barrel proper, or don't clean it at all and the barrel rusts to H-E double tooth picks,
They loose interest because it's not easy and part'm out.
All or many of the parts are interchangable, so I don't see a big deal with it,,be smart in what you pay for the individual items and you can put together a gun many times for alot less than a complete rifle anyways.
Complete rifles can be had for 200-300 or less depending on your region, so go from there.
It's hard to wreck a lock or trigger,,If a stock isn't cracked they're easy to re-finish,,
Finding a good barrel is the trick, try to find one that's "money back" if not satisfied, or at least one that has a good "bore" photo and detail. And stay shy of "as is" deals.
What drives me nut is when they pull the rail and thimbles from the barrel,,come on man,, it's part of the barrel.
I nearly got burned on an e-bay barrel for $75, the guy said the rifleing was good, "as is". When I got it it was rusted freeking BAD!! Used the Paypal arbitration thingy and ended up getting $55 back, which was OK with me, the sights where worth the $20. And I still have the breech plug and rail/thimbles.