itch.io

Amazon has plenty of PSVitas, I bought my first one from there, about 2 years ago, and it was in excellent condition, the second one was in near mint condition, and I payed even less, the real money eater is the proprietary memory cards for the PSVita, the largest one Sony made was 64GB, one of that size can cost just as much as the PSVita itself. I just looked some up, and the price range I saw was $200, to $270, not sure it they have memory cards in them already, either way a modded PSVita is required to play this, or any PSVita homebrew games, and modding one now days it really easy.

There are also really solid PS Vita emulators out there.