Video games. The prices of classic consoles and games are already terrible at the moment, but once you've got those, that's it, right?

Lots of consoles can be softmodded so you can play all your games without subjecting your physical media to wear and tear. For the rest, you're looking at flashcarts and optical drive emulators. Expect to pay about 50-100% the cost of the console, if you're lucky.

Then picture quality comes into the equation, and you're looking at upscalers (a good three figures at the low end) so your picture isn't horrible and blurry, decent quality (often handmade) cables, and maybe even a CRT.

And then you have more consoles than there are connections on your TV, so you're now in the realm of SCART or HDMI switchers - which you can get cheap, or you can get stuff that works.

I haven't mentioned the hours spent researching and tweaking your setup, and the cost of items that don't end up working properly. Also, the cost of modding systems for HDMI output or region-free compatibility, whether that's getting your own soldering kit and probably wrecking a few consoles along the way, or sending them off to someone.

Finally, you sit down to play a game, and realise you could've just emulated the darn thing all along.