I'd bake your video card, you'll need to replace the thermal paste but you can get some stuff dirt cheap online at places like DX. But it seems like you need something now, so I'd get the cheapest paste I could get at NCIX or something.
NCIX.com - Buy GELID GC-EXTREME Thermal Compound 3.5 Grams With Applicator - TC-GC-03-A In Canada.
The stuff linked above is really good and comes in a pretty big tube, not to mention it's way overkill for what you'll need it for, but hey it's 5 bucks.
If baking fails, you really just have 2 options, get a used 260/5770 for cheap or get a low end card. Something like the 430 should be able to manage well enough as long as you're not expecting any real performance. I'm not sure what kind of digital art you'll be doing, but you should be able to get playable framerates for most games as long as you crank down the settings.
Zotac GT430 at Amazon, PM it at
NCIX, you'll get the MIR. (which is USD BTW and mailed out of BC) That's $69+tax-$20USD, well within your budget.