I always avoid mac_geniuses as if it was the plague.
9 times out of 10 the hacked roms from strangedogs will work. Just keep in mind of the vRam and the GPU core.
Having bought something from practically every single Mac video card seller on ebay at least one time or another over the last 5 years (some even long since gone from ebay), I can pretty much assure anyone that Mac_Geniuses is BY FAR THE BEST! His shipping could be faster, but he knows Macs well enough to solve problems and was able to solve an installation issue for me very quickly. If I were slightly smarter, I would have realized his auction had all the pertinent installation info I needed, but oh well. Most of the other ebay sellers I've bought from either aren't even Mac users at all or they don't answer their emails as quickly or they just sell junk. Mitch answered an email within an hour! And the problem was solved in an even shorter time. And the video card is still in use today.
Not that there aren't some other good Mac ebay sellers. I've also bought from Yoyomarv and he's also a real good one, but unfortunately he doesn't sell much these days.
I've also bought from Applemacanix (way back when he was Powerbox_Technology) and he's reputable, but didn't answer my emails quickly and his only solution to a problem (that someone else eventually fixed for me) was to return the card for exchange or pay a $10 restocking fee. No tech support whatsoever other than to return/exchange the item. If you check him out at http://www.powerboxtech.com
, you'll see why (click contact and you'll see his ebay name). He's a Linux company. Apparently, he just sells Mac stuff on the side and I guess he just doesn't know much outside of Linux. Sadly, that's how many Mac sellers on ebay are these days.
I've also bought from ebcwizard (back when he was honor_dj before ebay suspended him). The item worked, but not exactly as described. Once again, email contact was slow and the explanation/solution for a DVI issue on the card (it didn't work) was, well, not satisfactory. I eventually got rid of that 5200.
I don't know much about local338, but he seems to have great feedback. But, he's in Hong Kong.
I've also purchased stuff from some of the Strangedogs.proboards40.com forum moderators (Tewlboy, Rubytuesday, NVFlash, etc...) and they are without a doubt some of the sketchiest people of all (several have been suspended by ebay) and they also seem to be the same people who over and over post on different forums under different names saying not to buy from Mac_Geniuses, just like the post above. Obviously, there's some grudge match going on since none of these people who post this crap ever say they are a customer of mac_geniuses. They either make ridiculous claims that don't seem to be true or they just do one of those, pssst pssst, don't buy from him things. That is just dishonest.
And they've even given you bad advice on the best Geforce 6800 to buy to flash yourself!
The Xtreme or XT 6800s won't work that I'm aware of. You need either a GS or a GT.
Get the Dual-DVI XFX Geforce 6800GS if you can find one on ebay. And yes, both DVI ports work and no hacking of the rom is required to flash the GT rom on it. It won't drive a 30" Apple, but it's the best of the 6800s. Trust me, I've tried a few.