Im guessing you are looking for it to last a really long time..
Most of the powerful gpu based laptops start at $1200....
http://computers.toptenreviews.com/gaming-laptops/Before you buy make sure you have these:
a good 1080p display with 120hz or less....very costly!!
a good gddr5 gpu with 2Gb vram......cost goes up
upgradeable memory for future upto 16GB 1600mhz---The MAKE or BREAK deal....more important than cpu and gpu.
my recommendation would be to get a cheaper cpu with focus on ram expandibility and modestly powerful gpu(2GB gddr5 vram)..
Intel cpu's are great for a laptop and amd are not.......but you will save hundreds of dollars.
or better still try for 2nd gen i5 or i7 cpu
also make sure there is no OS installed although on the cheaper ones it will be.
i have used a hp pavillion g6 2005AX trinity laptop with amd apu a8-4500m and crossfire gpu.......a solid and powerful low budget gaming laptop that works fine with Ultimate Edition....
for intel(budget)
HP Pavilion DV6-7040TX
a laptop with 16 gb
Dell 14z Ultrabook
You will encounter problems with compiz on Ultimate Edition....most of the problems are inherent of Ubuntu 12.04....a quick fix would be to install the liquorix kernel....and then the gpu drivers.
No linux is a walk in the park for out of the box.