Reddit mentions of ASUS 15.6" Laptop 8GB 750GB | U56E-EBL8

For that kind of money, i'd suggest building a desktop.
Not only can I run FTB at around 60-80 fps with everything on high, but it only cost me around 470 ish dollars (without a hard drive or OS).

My Build:

Gigabyte B75M-D3h motherboard
HD radeon 7770 2GB GPU
intel Celeron G540 CPU
After market CPU heatsink
CX600M PSU
ATX-238 Raidmax case
2X4GB ram sticks

A SSD will be about 1$/gig
or a SATA hard drive will be cheaper

an OS is around 100$

total around 700/800



if you're set on a laptop, i'd suggest a ASUS or Lenovo laptop.
this ASUS latop here
http://www.amazon.com/gp/offer-listing/B007S63H1S/ref=dp_olp_0?ie=UTF8&condition=all
is pretty nice, it was the one i owned prior to my desktop and ran FTB rather well (around 20 fps)