You'll need to at least do the digimod to your UA-5, its quite simple, just cut a small trace and solder a tiny wire. Without that you cannot run it into a jb3.
You have many options for good mics in that range. Buy used from TS members to get good prices and safe transactions.
AKG 391's - $400 (
http://taperssection.com/index.php?topic=63061.0) I had these mics and kept changing but going back to them. Consistantly pulls great tapes for me. You'll find alot of tapes wiith this combo.
Audix 1290's - $550 (
http://taperssection.com/index.php?topic=64775.0) great mics, this seller is selling both Card and hypercard caps with it, so you get more options. The sound of these has always sounded similar to akg 480's.
Studio Projects C4 - $230 (
http://taperssection.com/index.php?topic=64932.0) often compared favorably to the akg 391's. Comes with both card and omni caps as well as t bar and shockmounts. This particular pair is basically unused. Tim (raoulduke) is a very trustworthy guy who takes good care of his stuff.
Good luck, these are 3 of the more popular mics in that price range. If you scour hard you might be able to find a pair of akg 461's for $500.