I changed out a logic board a year ago, ran about 300-350$ on eBay for a used one. in the end, I spent more on the laptop than it was worth! sadly..
if you have a price in mind or whatnot, pm me and we can talk. I love tinkering when the wife lets me!
MacPro 4,1 2009 6 core 3.46 w/BenQ 32" 4K BL3201PH / 980 Gtx TI Amp Extreme
Mac Mini 2006 (kids)
Synology DS1010+ w/ 15TB Raid 5
2x Apple TV 1 160GB w/ crystal HD decoder