Pedal side uses a standard 410 chain or 1/8" bicycle / bmx chain.
Not sure on cost, but might be cheaper than garage door. And you shouldn't need anything heavy duty unless your trying to pedal start a seized motor

Also, from my first question... Chains are organized in a pretty easy to use number system (410 - BMX, 415 moped/light industry/ 420 motorcycle) etc, etc...