hi! i've been baking gluten-free bread in my breadmaker(s) for the past few years, and i was really apprehensive and pessimistic before I started. i read up a lot, read thru different reviews, consulted gf websites, and bought the book the gf gourmet bakes bread (i actually don't like that book, b/c we're also egg-free, and also so few of her recipes rely on sorghum, which we use a lot of b/c of its mild taste).
anyway, in my experience, the only feature you really need to be concerned with is a "quick" or "rapid" cycle-- this means that there's only one "punch-down," which is better for gluten-free breads. the gf flours don't need that second punch-down cycle, because they don't have the elastins that gluten flours do, and therefore don't need the work-out that gluten flours need to make them more pliable.
i've used the breadman ultimate tr4000 i think the number is and also a cheapy sunbeam one i picked up at a garage sale and both make really good bread.
i second craigslist. there are an absolute TON out there, b/c so many people like the *idea* of homemade bread but then find they don't have the time. for us, it wasn't really a choice, b/c we haven't found a gf bread out there that we like, and they're all too expensive, anyway!
barb uses a mix exclusively-- y ou might pm her to ask what it is-- and there's also a TON of gf bread recipes-- which are easily adapted to the bread machine, if not initially written for it-- on recipezaar.com.
my friend said she had heard an interview about a mom who started b aking all her own bread. the mom said something funny-- like, the worst thing about baking yoru own bread is that your kids eat it up.

(meaning, then she had to keep making more... ha, ha!)
good luck!
alycia