Usually, I build a system myself. But because it was cheaper to build a system through ibuypower.com than from individual parts, entirely because individual graphics cards are so ridiculously priced currently, I went with ibuypower.com.
I've never used that place before. Their builder functionality on their web site is quite good. Prices were good. (Except for RAM, for which their prices aren't good -- so I bought machine with lowest ram I could, and will just swap in ram I want from Amazon.)
I'll let folks know what the machine ends up being like.