I had a friend send me a GTX 295, EVGA 780i, memory and so on a couple of years back. We decided to set the value at $200 (I paid $90 for the 295) to cover it just in case. It was in a big box, too. IIRC shipping with USPS was around $35. I got stung for duties, but only about £20 iirc. You can send a gift up to $40 IIRC.
It depends, I bought a 480 and 580 together a couple of years ago (so the 580 was quite new) worth 600usd+ at the time I think, and it went through with no issues.
The British customs are a law unto themselves I recently bought an item from the US worth £18 it got through without any charges a week later I ordered the exact same item this time I had to pay both VAT and handling charges £2 VAT and £12 handling
Are you still looking for something? I'm upgrading my current rig to mITX to save some space so have an AMD Phenom 3X 720 CPU, MSI 770-C45 motherboard and 4 GB of 1333MHz RAM (can't remember the brand but it's proper branded one with a nice heat sink!) spare. I felt the CPU/motherboard combo was the best value for money combo at the time and everything works well. Probably about the same performance to a Q6600. Not really thought about a price but how about £80 including delivery?