even a cheap electric drill is 40$ most as well have a clutch that will burn with exessive reverse RPM's electric starters are free wheeling,when the engine starts the drive shaft spins freely without restriction,if you take a close look and compare the motors a starter is Quite a bit larger, the RPM's provided by a drill is about 600,a electric starter is about 2,500.
there was a large thread on this subject a few months ago so I did some homework back then.