There are also the rear hub geared and gearless motors for simplicity sakes. It seems like he just needs a little power. The gearless hub is cheapest but has a cogging effect where the magnets cause some freewheeling resistance while the geared hub reduces this. But, if he gets a 250W gearless I don't think the cogging will be that bad. There are 12V cylindrical lipo batteries but they are rare and expensive, as people mentioned most use 18650 cells grouped to provide the right voltage and capacity.
Besides, SickBikeParts there are also other more branded mid drive electric motor manufacturers. But, SBP do provide the best value for the buck in terms of power. Mid drive is generally more expensive and requires more setup time and tools. However, they freewheel (no resistance), higher efficiency in terms of gearing and drive gear, and have higher torque (efficiency) than other electric motors.
I am planning on building a "different" type of ebike and am going for the cheap 500W rear gearless hub motor ($135). Ideally, I would like to have a 500W Bafang, Yamaha, or Bosch mid drive with a kick ass carbon fiber fat bike but... that isnt really necessary as a proof of concept.
Also, 3000W is way over the legal limit for an eBike. Not that anyone might care if you are actually pedalling but if you are going 45 mph+ on an eBike and get stopped by the police or get in an accident then it might cause some problems. 750W is the federal legal limit and there are additional classifcations beyond that depending on your state. Enjoy the ride!