What does renting a few more times cost you? With regs, my only concern with second-hand options is whether you need to get them serviced (which can suddenly make the price much less attractive). We bought everything new in the end because I couldn't find local 'great deals' on used gear that I wanted to own and represented sufficient savings. Even then, at the locales where we dive, we figured we'd break even after about 6 weeks of diving, and the comfort of having properly fitting gear that I'm fully familiar with is worth something as well. A friend of mine who is less fussy bought second hand stuff from his LDS, who also provided serviced and (limited) warrantied materials.
If I were stateside, I would have a good look at Deep6 regulators/SPG, which sit at a real sweet spot for value (including servicing cost down the line), certainly in the US where you don't have to deal with expensive shipping, taxes and import duties (which makes them far less interesting for me as a European).