I have a couple of waistcoats with lapels that I bought locally from "old west" type stores. The brand is Frontier Classics.

http://www.wwmerc.com/cgi-bin/Catego...920&type=store

The problem with buying waistcoats that aren't made specifically for kilts is that they can be a little too long in the front, interfering with the sporran. But if you buy a straight-cut bottom, it tends to work OK, depending on your torso length.