I posted "wanted" ads on Craigslist repeatedly. After a few months, I got a hit. It was a HS crew coach selling off old equipment. I bought 3 model Bs from him, and sold off 2 of them. The proceeds from selling the 2 rowers paid for the C2 that I kept, and then some.
For the sake of reference for this thread, I sold them for $340 and $350. Both were in good condition, and freshly tuned by the HS coach. "Market" prices seem to be a bit higher here than on the east and west coasts.
If you have the time to hold out for a good deal, consider Craigslist.