Quoted from FunkyFreshWalrus:
I don't really sell anything on the market, but if it prevents anything from being listed and available it's a bad thing I think. It's one thing to pay a fee for a whole machine, but a lot of the small parts, mods, etc will never be worth it. Also there is a lot of fan stuff on this site that I don't people are making much of a profit on, so they probably just won't list them.
I decided to donate when I was able to successfully find multiple odd parts I would never find elsewhere. Not via the market, but by talking to people on the forums. I think if you get a regular benefit from the site for any reason you should donate or support the site in whatever way you can.
Personally, I haven't had any luck selling anything on pinside. So far, everything I've sold has been on other sites, at shows, or unadvertised word-of-mouth.
On one hand, I don't want to be nickel-and-dimed on everything. On the other hand, I don't want to pay a flat fee for something I don't actually use.
In the big announcement thread, I saw there was some interest in vendors/businesses buying some ad space, so that might be something worth looking into. And ads like those wouldn't be annoying like randomly-generated site ads can be, since it's likely something that a good portion of visitors would be interested in anyway. Heck, in the profile settings, you could even have options of what types of ads you would want to see (pins, mods, replacement parts, lighting, repair services, literature/mags, manuals, etc).