You can find motors like this at most surplus stores. Looks like something similiar to a turntable motor like in a microwave. The adjustable coupler could be useful though. It looks like it's nylon with three nylon screws. The motor is not much over 1 1/2 inch in diameter from what I can tell from the picture and comparing to the chuck.
$22 Not sure if it is worth it unless you have a particular use in mind. It certainly would not be powerful enough for most props I see here. Now a rotating Wiches Cauldron it could likely handle.
I have not made this prop, but from what I have read, I suspect that motor will not be powerful enough. There is quite a bit of linkage and leverage involved in a FG. I think the motor you are looking at is designed for a turntable and may not be built rugged enough to deal with FG hardware.