Will do everything you need for 50$ under your original budget. You will also get way better battery life than going with those other solutions. Play minecraft on the integrated gpu and battery for hours and hours. Switch to the dedicated and plug in for the big stuff. Using a similar machine and it overclocks easy if you need it and performs great.
LOL. Yeah thats the way it is with laptop shopping. You start out modest, and then end up believing you need 2grand worth of I7 and 580gtx to game. It is hard to believe that 600 nowdays will buy a pretty decent machine. I guess people get convinced that they need 60+fps at ultra settings when really your xboxes and such run alot of stuff at 30-40fps and low equivalent graphics and the masses are happy.
If you truly crave the ultra performance then a laptop is not the way.
I subscribe to the idea of building a desktop: you can very easy upgrade your system. The i5-2500k processor is also quad-core and supports strong OC; the mobile i5 is only dual-core.