Lets say I have a target budget of about $600, with some flexibility.  What kind of setup would you recommend, and what should I look for or avoid?

So far, I have all of my other scuba-equipment, including a dive-computer.  Most of the diving I've done so far is relatively casual (average 60ft, 70F degrees), but it would be nice to have a regulator set capable of handling varying environments.

Scubapro
Have some 30plus years old
Just get serviced properly

@Marie might know.

@SlugMug

I'd suggest Dive Rite. Breathe as well as my much more expensive Apeks.

Dive Rite

This package is $649. Free shipping. Will come assembled. I have DR regs and really like them.

@jerrwhy01 has taken these regs many hundred of feet back in caves

I'll put that on my maybe list.  I'm not familiar with that brand, is it fairly well supported brand in terms of long-term support, parts, etc?

I see SP recommended a lot.  Is there anything I should look for in terms of features or models?

edit: I ended up going with a used Scubapro MK10 & G250.  I'll get them serviced when they arrive, but they seemed to have fantastic reviews and I've heard SP is great in terms of long-term support.

edit2: How strongly would people recommend for/against self-servicing regulators?  I'd say I'm mildly competent with tools, assembling/disassembling most things, and had little difficulty with learning how to assemble AT15s from scratch.

I got lucky on craigslist, and ended up with 2x ScubaPro G250, 1x ScubaPro G200, 1x apeks atx200, and 1x apeks at20.  So I now have more regulators than I need (although most are due for service).   I also ended up with a Shearwater Predator dive computer.

I think I've decided I'll use:

* The Apeks ATX200+AT20 set as my primary octo
* ScubaPro G250/G200 is a backup (I've seen other divers have regulator-issues at the surface)
* ScubaPro G250 on a pony-bottle.

I just need to decide whether to get a 19 CU or 30 CU pony bottle.  I'm leaning towards 19L, because it's only for emergencies.

Actually get a 40. It disappears underwater. Plus they have much better resale value. Tech divers always want them.

I assume you’ll be diving locally?

However if you have a regular jacket BC (yuck), you probably won’t have D rings in the proper places to sling a 40. So you’ll be stuck with a 19.

Honestly, I wouldn’t bother with a pony. Eventually, it will become a pain in the butt and you’ll end up leaving it at home. If you want a redundant air supply a set of baby doubles works great for open water. Baby doubles are essentially a pair of LP-50’s with a manifold. However, if you insist on a pony bottle then follow Marie’s recommendation for an AL40 as it probably has the greatest resale value.