sloan express has that connector for $15.99 in their catalog.part #111232
their phone # is 1-800-934-9777.this is for the plug only,no wiring.
The $100 kit is not just a plug in. Would include curcuit breakers, wiring, etc (instructions geared to a Deere tractor). The Deere 3 prong plug does not have to be used, it comes standard on current Deere tractors, utility size and larger. You can simply cut that plug in off and use any style plug in that you desire. A three port style is nice because you would have a live as well as a keyed wire if you hooked it up in that fashion.