Built my own. All I needed was motherboard, proc, and RAM, recycled the rest of the parts from my previous desktop PC. (Then recycled the remaining parts down to my son's PC.)
While I have spent some money on this system; I would still gladly buy a Mac that is based on i7 if/when it comes out. (Based on the desktop, not server procs. A Mac Pro is still out of my price range.) While a headless mini-tower would be nice; an iMac would be okay, too. (I still don't have a 'good' monitor for my PC; relying on an old Blueberry 15" Apple Studio Display and a 19" ViewSonic CRT that displays very high resolution, but is a complete power hog; so I usually just use the Studio Display.)
I am one of those who believes that the two products I really want, Apple no longer makes:
1. A high-end headless desktop computer; not a workstation, not an all-in-one made with laptop parts. (The beige G3 was the last computer that fit this bill. The Cube was close, but still too much of a compromise of form over function.)
2. A true subnotebook. The 12" PowerBook was the last Apple notebook I really liked. The MacBook Air could have been perfect, if only the footprint had been shrunk to the minimum necessary for a full-size keyboard, like the 12" PB was. (The 2400c was the last one that fits this to me. The 12" PB and the 12" iBooks were oh-so-close, but still, ironically, went for function over form too much for this category! Again, the MBA would be absolutely perfect if it had an 11.5" screen.)