I try not to overspend on older computer hardware, especially if it's something that has been mass-produced to the point where it's commonplace. The ONLY time I would overspend is if I felt that I desperately needed something and I had the money for it, even then I would have a bad feeling like I threw away money that I could've used on something more reasonable.
I remember when Gamecube games used to be commonplace and cheap, now they go for varying amounts of money (often at ridiculously expensive prices), because of that, I regret not picking up certain games for that console when I had the chance. Admittedly, I ended up paying $60 for a copy of Melee last year because I felt like I really missed that game to the point where I had to get it while it was still at a reasonable price because who knows if the prices for Gamecube games will get worse like what happened to other things in the retro gaming market (notably 3dfx graphics cards).
There are certain price points that I refuse to go above. For example, I've seen people sell CRT TVs at insanely expensive prices lately regardless of how high-end they are, I once saw a 13" RF-only Sony TV at the Seattle RE-PC at an asking price of $120, which is too expensive, I wouldn't even pay $5 for that TV knowing it only had an RF input as RF-only TVs usually have a hot chassis which makes them hard to mod for RGB or even Composite video. At a price like that I'd rather just buy a Retrotink and play my classic consoles on a modern TV. There were also other examples of insanely priced hardware at RE-PC (notably vintage Macintoshes and sometimes their CRT computer monitors), the Tukwila RE-PC is even worse than the Seattle one in terms of pricing from what I've heard.
I know I've used video games as my examples, but this also applies to old computer hardware.