I did 4a), replaced every component on 2010 Sirrus Sport, except frame, fork, headset and brakes, then bought new frame, fork, headset, and brakes to build a new bike. Rebuilt Sirrus to stock, then bought parts to make stock Sirrus into single speed knobby tired creation. Now I shop for 4c) when I'm not riding.
But on a positive note, my neighbor just got a $10 Specialized Rockhopper from CL, and is buying the leftover Sirrus parts for $35. So $2000 invested, $35 return.. At this rate, I'm ahead of the NASDAQ