The best place to get replacement parts like lasers would probably be ebay. They have some cheap ones for sale. Emphasis being on cheap. Just remember, you get what you pay for. I'd go for a used Nintendo brand myself. If you are looking for motherboards, I would use Google to search the NES Repair shops. I have seen motherboards go from anywhere from $15.00 to $40.00+, so don't get taken and be discerning.