i love this thread. and in the Year of the Saturn (20th anniversary) no less!
prices are spiking, especially on US stuff - even common ones! much like the turbo scene, there's better deals on the import end except for the big name J-only ones. i can't recommend enough the idea of emulating, watching youtube etc about the big ticket items to see if they're really worth it to you, then patiently holding out for a deal - sometimes craigslist, mainly forums though. for me, a few japanese sellers on ebay were totally worth it for SHMUPs/fighters/run-n-guns etc, usually buying at least a few at cheap prices to balance out the shipping (which also isn't bad once combined). i got a model 2 with unibios + CD-r support mods for less than $100 about a year ago, and it's been the single most played console i have since then, including the PS4.