It all depends on the condition really, but even then, that isn't a good way to tell, there are a fair few people on this forum that have bought a second hand turbo, and it's been fine, then 2 months down the line it goes, then there are also others who have bought a second hand turbo and it's been fine for the rest of their golf's lifetime.
So really it's up to you, and how much you want to spend, but ideally just buy a cheap turbo then just get it reconditioned