+1 to this.
I like Carvins and have owned a few over the years, some new and some used. Used is a great way to go if you're either patient or not that picky. Personally I've been somewhat seriously watching for one that is close to the specs I'd want if I got another one new and haven't seen anything close in over a year.
At the moment I own one Carvin and it is also a bass that I doubt I would find another one like it on the used market. First because I was pretty specific about the finish I wanted and secondly because I talked them into doing dual humbuckers which apparently they really don't do often on a B4.
So I guess my answer is that it's worth it if you think you'll have trouble finding one you want used.