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It depends. If your Mac is old and/or it has got an integrated graphic card (an Intel graphic), the repair will be very expensive or it would be worth to buy a new Mac.
If your Mac is recent, there's no reason to buy a new one because it can work correctly for the use you want to give to it
Your Mac was covered by a replacement program. Macs with the NVIDIA GeForce 8600M GT have got a defective graphic, so it must be replaced, but it expired, so now you will have to pay to repair the Mac. If you think that your Mac can be useful for you, take it to an Apple Store to get the Mac repaired, and if not, buy a new computer
That's because the program expired on December 7th. Also, you have to tell them that you want a new graphic because of this replacement program, because, as fas as I know, they don't know if your Mac has got a repaired or a defective graphic. For example, I took my iMac to replace the hard drive because of a replacement program and now, with a new hard drive, it still appears as covered to replace the hard drive