I typed a reply to your post yesterday but by the time I hit Post, your post had gone. Can't remember what I said, now.
Science_Research:
I am looking for 12 - 24 volt dc Arduino compatible motors.
No 12-14V motor is compatible with Arduino- I'd say no motor is in fact, not even a teeny weeny 5V one. You'll always need a driver of some kind in between, from a lowly NPN transistor up to something with more oomph. Have a look here for a start, but of course you'll need to know what current your motor is likely to need first. And that depends on the mechanical considerations.
You could explain what one of these is, perhaps:
Science_Research:
I was also looking for suggestions on what Arduino to use for a biomedical scooter.