I've bought two custom rigs from this place in Saskatoon, Sask. You go in, sit down and talk with a knowledgeable guy (or girl) and component by component hammer out a system. They have good warranties and support, in my experience.
There has to be a similar business somewhere not too far away from you. Look for a place that specializes in the latest custom PC's and parts, and have up front pricing. There is a definate advantage in a face to face meeting with a computer tech., as opposed to a microwave and engine oil salesperson. You can avoid all sorts of bottlenecking and incompatability issues that come up as you are selecting your system.