I'm in the process of building up my first singlespeed (and fixed if I go the flip flop hub route) and wanted some advice with wheels. I was considering upgrading the wheels on my road bike, and using the old wheels on the new singlespeed. The current/old wheels are built with a cassette and specialized hubs.
How much of a difference does getting a flip flop hub and wheel built (around it) make vs. adapting the cassette system? Is there a place online that sells built up wheels that I should consider?