any mod that's WAY overpriced. fixing up a beater TZ and making my own DIY mods. making a gumball mod w/ color changing LEDs. price of parts i don't already have around lying around is $5-10 at the most. camera mod: $5-ish for a cheap camera keychain from a hong kong seller. started researching the TV mod and looks like i could do it for under $50 easy. if you know basic electronics and how to solder, these mods are super cheap. and you have a whole forum of folks to help too.
on the other hand, you have the piano mod, which can be gotten for less than $100 and considering the work and specialized tools that go into molding, it's not a bad price.
action figures: a couple is okay, but can easily go overboard. whoever limited it to Todd McFarlane figures had a good point. way better than some cheapie looking action figure. the marv TFTC electric chair mod comes to mind as a great action figure mod.