Ewwww. With all the bed bugs and such being spread around, you'd be nuts to buy used upholstered furniture on Craigslist. And, wouldn't the people who are willing to spend more for higher quality furniture also the ones more likely to be able to spend more money on veterinary care?
But, again, you admit that during training, there will be times that the cat scratches furniture. That's likely to cause some damage. Why would you begrudge someone who has nice stuff, but would also like a pet?
(Me: presently, I have average furniture, and neither cat scratches the furniture. But, the point I'm making seems rather valid.)