newegg sometimes has refurbs.. i cant really recommend that to a inexperienced user, but if you want to take the jump, go for it.
i try to not spend over $50 on a PCI card and the refurbed 5200s do nicely. i would try to get one with 128bit memory or the 5200 ultra if you go that route though.
the 9100 is a good card as well, but is DX8 and at this performance point I dont see much difference.
in the high end i have liked some of ATI's stuff (9700/9800), but since you wont find a stellar PCI card, buy on driver quality/compatibility (nvidia).
DX9 functions are merely a bonus.. some can actually speed up parts of a game (and you can disable certain taxing DX functions in most games).
but if you play some doom3 or something similar (prob only playable at 640x480, at least my personal PCI 5200 does smoothly at medium quality), you can enable features like "heat haze" that are not available on DX8 cards.
just an example. someday, even your OS will use DX9 (and better) functions. i know the next windows will use the next version of DX to accelerate its 3D interface.
the fact you cant find a $50 5200 might just be bad luck right now. I was going to order a dell 2001FP and now the price went from $599 to $799 on dell's site! argh!