Usually the coin doors Happs sell come with coin mechs. The $24 states it comes with a .25c coin mech. Not sure about the 96$ one but I would assume for that price it would.
The 96$ appears to be a fully contained sealed unit. Why the price difference?? not sure, appears to be stronger built.
If your looking for a single slim vertical coin acceptor the 24$ would be fine. If you expect a bunch of drunk baboons will trash your machine and trying to steal your tokens then the more expensive one is what you need.
If you have any other questions, I'm sure Happs would be more than happy to answer any questions about their products.