Define inexpensive, define good, etc. You should be able to narrow down for yourself which places fit in your budget then read or ask more about them. See if Habitat, Sunset, or Lions Dive are in your budget. None of them are fancy but could do the job.
You don't absolutely need a car anyplace but nice to have especially in some cases. Depends where you stay and what you want to do. Some areas, there is a decent amount within walking distance and taking a cab downtown would be reasonable. Some places are pretty remote, and while they may have shuttles, the schedules are often not useful if you're diving alot or want to go downtown for dinner. So you might pretty much be stuck there. Lion's Dive you could certainly do without. Habitat you might miss having a car as it's far from things and the food will get old quick. People seem pretty content with the AI food plan at Sunset and their flexibility with the shuttle so you could do without.
I haven't used the dive bus, but I think you'd be able to hook up with a buddy that way as easy as being on a boat. Assuming they pick up where you're staying. And at the real dive resorts you might have some luck hooking up with other divers for shore diving.
