Hi and welcome to forums
Building one yourself is quite easy, theres a very good guide at the top of this page by greywolf which walks you through it, all you need is a medium size Phillips screwdriver and a bit of time and patience
This build below would suit you, wasnt 100% sure which case you wanted, included the HAF X which is nice and big, but there are smaller variants available too, has good quality monitor, good gfx card which supports 3d and the glasses set, based around the new i5 Sandybridge stuff which is best you can get at the moment, feel free to ask if you have any questions
OcUK GeForce GTX 570 1280MB GDDR5 PCI-Express Graphics Card £275.99
Benq XL2410T 24" TRUE 120Hz 3D Widescreen LED Monitor - Black £275.99
Intel Core i5-2500K 3.30GHz (Sandybridge) Socket LGA1155 Processor - OEM £171.59
Coolermaster HAF X Gaming Tower Case - Black (RC-942) £131.99
Nvidia GeForce 3D Vision Kit £122.54
MSI P67A-C45 Intel P67 (Socket 1155) DDR3 Motherboard - (Sandybridge) £89.98
Microsoft Windows 7 Home Premium 64-Bit - OEM (GFC-00599) £81.98
Corsair TX 650W ATX SLi Compliant Power Supply (CMPSU-650TXUK) £67.99
Samsung SpinPoint F3 1TB SATA-II 32MB Cache - OEM (HD103SJ) £41.99
GeIL 4GB (2x2GB) DDR3 PC3-12800C9 1600MHz VALUE PLUS Dual Channel (GVP34GB1600C9DC) £37.99
Akasa AK-CCX-4002HP Venom CPU Cooler (Socket LGA775/LGA1155/LGA1156/LGA1366/AM2/AM3) £35.74
Pioneer 24x Internal S19LBK DVD Rewriter including Labelflash SATA Retail £19.99
Sub Total : £1,196.45
Shipping cost assumes delivery to UK Mainland with:
DPD Next Day Parcel
(This can be changed during checkout) Shipping : £27.55
VAT is being charged at 20.00% VAT : £244.80
Total : £1,468.80