Thanks for all the comments, everyone!

Some followup questions:

- Currently there are a few Beselers and the above mentioned Saunders enlarger on my local Craigslist. Frankly, they are cheap enough that I probably should buy one of each, but otherwise, how do I choose? From what I gather, the Beseler is far more common (true?) which suggests to me a greater availability of spare parts over time.

- It also seems like these were setup for 35mm. Which means I'm going to need to source film holders and a lens? Doc W commented that the lens is the thing to put the money into (makes sense to me). Since it looks like I've got plenty of headroom in the budget here, what specific lens would you recommend? From what I've read, 50mm lenses are the standard when working with 35mm, but for 120 (more specifically, 6x7 coming off my RB) I've read stuff that says 75mm up to 105mm. Does it matter much where I fall in that range? What are the functional differences between 75mm and 105mm? Right now there is a El-Nikkor Nikkor 105mm f5.6 on eBay for $135 and an 80mm for $50. Is that the sort of thing I should be looking at?

- If I go with the Beseler 23C, I think I need the "8070" negative carrier for my negs. Does that sound right?

That "Way Beyond Monochrome" book looks fantastic! I'm all over it!

Thanks again for all the advice.