Update: I was able to get the machine repaired. Micro Center changed out my PSU and one of the RAM risers. Total cost - just under $400, including labor.
Relief.
Nice! I'm glad to hear you got this repaired. I just came across this post and it made me laugh only because it's one of those stupid things that happen in life. But, believe me, I felt your pain and sympathized.
Can't believe someone recommended just buying a new machine. It's sad that we're moving toward a disposable culture. That's why I love the Mac Pro forum here, though. 99% of the people are the opposite and all about squeezing the most out of every machine, old or new.