I've stealthed with my UA-5...but I had to use Jedi Mind Tricks.
If I were to build a STEALTH rig for $600 I would buy a used R-09 and spend the rest on a the nicest set of Church Audio mics and Church Audio Pre-amp, that I could get with the remaining funds.
I personally prefer to stealth with omni caps (so I don't have to stand so still), but if you go to shows with chatty people you might want to go with cards. Ideally get both so you can swap them depending on the situation.
My thoughts precisely. For versatility, get a stealth rig first. If you ever want to tape another band, you won't be stuck with an open rig and regret it.
I throw in my vote for the Church Cards (I'm not a big fan of omnis) > Church Pre > R-09. Ideal stealth rig and still within your budget.
That said, I have stealthed with my UA-5 too, but admit chickening out once in a while, reverting to my stealth rig.