There not hard to get in UK either, and i know a few people who could lay their hands on them from the forces. Army surpluss shops might be to get them in aswell, not sure if you have them over there, but id be surprised if you havent.
Try either K-Mart or perhaps 7-11 might be a good bet, but they sell out quickly there. I always hit up the Piggly Wiggly down the street when I'm running low on bullet broof jackets and hollow-points.
At least get a Level II or even better a level IIIA (shouldnt be a big difference in the price). Forget about kevlar, now they're using new stuff like Spectra/Goldplex. Be sure that you're jacket is "anti-stabbing", not everyone is like that. Local dealers usually sells crappy-over-priced leve IIA which suck. A IIIA will keep you away (usually) from magnum .357, .44, even 5.56 mm at long-range.