my company has a T1 with TDM voice channels on it, feeding into asterisk. (hot tip: buy the digium hardware) we get new phone numbers routed to the T1 for $25 activation and, uh, $0.15/month. (couple hundred a month for the line itself.)

as for multiple phone numbers routed to POTS lines, i don't see why your phone company couldn't do it. you just wouldn't be able to tell which line the call was for.