You could buy an old inefficient ASIC miner on the cheap like an L3+. They're not really worth running anymore if you have to pay for the electric, but if the electric is free, sure.
I disagree with your thoughts. You cannot buy an item that someone else has thrown away. Right now, the GPU is the most sought after thing. Their costs doubled or even tripled. So why are there people who want to sell it? It was simply because its value was no longer there. Don't buy anything right now, especially second hand, you don't know when it will go wrong, you don't know how much it can bring you. But one thing I know for sure, it will cost you a lot of money to buy it, not worth a try 