Fax machine advice wanted

[redbird]

wilfulcait has pointed out that this new freelance gig means I should buy a cheap fax machine. I'm looking for advice on what to buy--and what not to buy.

I don't care much about supply cost: I expect to be using it (almost) exclusively for outgoing faxes, not incoming. Small is good, because I have no clear idea of where I can put the silly thing.