That's a tough one. A reg and BC are for your survival. A wetsuit or drysuit is best when it fits well, and a rental might not (besides other people have been peeing in it). A computer has to be learned.
If I was in your position, I would bite the bullet and look for a package deal including everything. Dealers, especially internet ones, run these all the time. It is always better to own than rent, and you can save a lot of dough that way.
Believe me, when I got back into this after a 20+ year layoff, the sticker shock floored me too. A lot of the gear I bought was used. No problem with that as long as you get it checked out by a tech.
And I loved the look on the dive shop owners face when I said the word "eBay".
