2008 M15x GPU replacement/fix

So, as noted in an earlier thread, my 8800m GTX burned through a component and though it still churns out some pixels today it probably won't last much longer. Especially since the now-overloaded remaining transistors/resistors/schwatever are pushing my temps so high that I have to place the laptop on an AC unit to keep them below 100C while gaming on low settings.
I've found some 8800m gtxs on ebay, usually running around $200. I've also seen where a gtx 280m was swapped into the m15x and ran with some modifications (due to voltage differences, I think). I was wondering if there are any other cards that I could swap in that would be cheaper than the 8800m gtxs are running now, or are at least an upgrade from the 8800m gtx and maybe worth a little more money. The laptop is probably well past warranty, so I am willing to make adjustments if necessary to handle a higher temp card, so long as it has a reasonable rate of success.

Thanks!