I believe Pendlay sells black training bumpers in pounds - these are the competition thickness ones, but not calibrated to competition accurate weights (plus, they're in pounds, which is obviously not acceptable for competition). Check the MDUSA website for them.
Concept 2 sells replacement parts for their rowers online; I had to get a new bungee for my Model C when I bought it off Craig's List. The bungee only cost a couple of bucks, so I imagine other simple parts would be the same.
And yes, I'm actually holding that handstand. Get on my level.