For comparison of high end stuff ... well I have chosen them quickly but the amount can be reduced I guess by another £300 if you choose the components properly. i.e. brand names etc.
All VAT including delivery.
1)Crucial RealSSD C300 256GB 2.5" SATA 6Gb/s Solid State Hard Drive (CTFDDAC256MAG-1G1)£487.61
2) Intel Core i7 960 3.2GHz (Bloomfield) (Socket LGA1366) - Retail Intel Core i7 960 3.2GHz (Bloomfield) (Socket LGA1366) - Retail £449.99
3)Gainward GeForce GTX 480 1536MB GDDR5 PCI-Express Graphics Card Gainward GeForce GTX 480 1536MB GDDR5 PCI-Express Graphics Card £366.59
3) Asus Rampage III Extreme Intel X58 (Socket 1366) DDR3 Motherboard £299.99
4)Iiyama ProLite B2712HDS 27" Widescreen LCD Monitor - Black £274.99
5) Corsair Dominator GT 6GB (3x2GB) DDR3 16000C8 2000MHz Triple Channel Kit (CMT6GX3M3A2000C8) £239.99
6)Corsair HX 1000W ATX Modular SLI Compliant Power Supply (CMPSU-1000HXUK) £184.99
7) Microsoft Windows 7 Professional - Retail (Full Version)(FQC-00133) £163.99
8. (water cool) Corsair Hydro H70 High Performance CPU Cooler (Socket LGA775/LGA1156/LGA1366/AM2/AM3)£86.99
9) Seagate Barracuda 7200.12 1TB SATA-II 32MB Cache - OEM (ST31000528AS)£52.99
10) Antec 300 Three Hundred Ultimate Gaming Case - Black £46.99
11) Samsung SH-B083L/RSBP 8x BluRay ROM / 16x DVD±RW Drive - Black (Retail) £43.99
Total : £2,722.72
Labour: 1 to 2 hours.
With near to the above spec = iMac £2,448.99 incl. VAT If iMac has the above specs it will cost more.