Do you know anyone in America you could get stuff delivered to. Motherboards, Graphics Cards, RAM and the Processor will come in quite a bit cheaper in the US. I built my system last summer and got everything except the PSU, case and DVD/HD Drives from the US. I got those from the UK and picked them up on holidays (Ireland is expensive compared to ebuyer
All you have to check is Revenue for customs info, or maybe your birthday is coming up and its your birthday present from the friend and you shouldn't have to pay tax.
PS: There are also mail forwarding services that include a tax calculator but they can be fairly expensive