Resource that can help find compatible hardware and motherboard

Need help please. Have two laptops fried, one 7 years old Pentium mobile 1.2 Ghz and another 3 years old AMD turion. Tried getting the laptops fixed by the manufacturers but the cost they are quoting to do that is more than most of the good laptops they themselves are selling in the market. Hence is not making any sense getting the laptop fixed from them. Have this bug of go green thing hence not in mood to give up so easy. Both laptops seems have the GPU chip blown off or may be some component around it. Both manufacturers claim there do not have replacement motherboards in market hence the fix is so expensive. Please help me know are there tools resources that can help me find what mother board I can buy as alternative to buying the original ones.