Spare parts prices

I bought a $50 1982 Coleman gas generator with a 5HP Tecumseh in avacado green just to get the motor. I'm putting it into a 1968 Powell Challeger mini bike. Everyone told me buy a Predator, nope these bikes came with a vertical cylinder! Too bad it didn't come with the rear mounted siphon carb and tank...08 Mazda 3 transmission solenoid...$223 at stealership, $19 on Amazon.