If you want to save money, buying used, with guidance, is absolutely the least expensive way to get a quality reg. I'd look for a MK5 or MK10 with a 109 (metal case) 2nd stage, or possibly a G250 or D300 2nd stage. You should be able to find one of those combinations for under $100, and you'll have a classic regulator that has been a mainstay of professional divers for decades. Regulators simply have not improved significantly; that's why there's so much hype associated with their sale. They are also designed to be completely rebuilt and last a lifetime if maintained well.
It is true that getting the reg serviced well is very important, and is an issue regardless of what reg you end up buying.
I concur with Halocline.
If you want to save a bit of money (no reason to do otherwise) without sacrificing quality, go with used gear. Contact the resident guru and ScubaPro tech, DA Aquamaster View Profile: DA Aquamaster - ScubaBoard Tell him about the type of diving you're going to do and hopefully he can set you up with a rebuilt so you won't have any worries.