I have no set price for gamescore. Let me know how much you want it increased and make what you believe to be a reasonable offer and if it's good then you've go it. Note: When I do it I will usually leave online Achievements alone as they can be more easily traced.
oh okay, i can see why you wouldnt do online achievenments, well ive still not heard back from "my guy" so i will let you know when i do.