Collecting vintage computers can be fun. I also personally think it’s great that people are interested in preserving that history. Where to buy vintage computers hasn’t changed much over the years. It just may take a bit more work than it used to.
Some people think old computers are priceless. Others think they’re worthless. I don’t recommend wasting your time with people who think a Dell Pentium III laptop is worth $300. Think of the times you found a jewel for five bucks and keep moving.