How much would it cost to upgrade my laptop?

so atm i have a budget of around �150 not much i know, anyway i have acer aspire 7540 laptop, its not too bad, but i wanna play games more often and at with little more graphics, its gets hot after about 10 mins of fable 3, new vegas, and prototype, ( i just ordered a cooler) anyway anybody know how much it would cost to take it too a store and get it upgraded? maybe a better graphics card and ram, its 3gb ram atm, if anyone has an idea i would apretiate suggestions :)