You really have to see what comes up in your region, within driving distance. In the Southern US for example, it's the 23c, they turn up quite often. Then do your research.
23c's and 67c's on eBay often have reasonable shipping (the 67c especially, a very sturdy enlarger for its size and weight) (I'm more familiar with Beseler). Also keep in mind that availability of lens boards, neg carriers, and parts vary regionally and by brand, but can be found on eBay and one or two online specialty vendors. Boards and carriers can be DIY solutions (1/8 plywood, cardboard, etc) if you have to hunt down the actual part though.
Many enlargers share some of these parts between models, so again, research helps. If a seller isn't aware his neg 6x6 carrier can also work on a pro-level 4x5, it can go a little cheaper.