I've had a Yamaha portastudio 4-track tape recorder for maybe 8 years now - the MT-50, it's served me pretty well. You can't get them any more (in fact I don't think Yamaha do analog multitracks anymore), but they brought out the MD-4 which was a digital version that recorded onto minidisks - which looked good.
...update: I've just checked the Yamaha site, they don't appear to do the MD4 anymore, or even the MD8 (the 8 track version). Ah well, if ya find a used one...
EDIT: Actually, I've just thought, I probably don't need my MT-50 anymore... There's a possiblity I could sell it to you. I need to get a replacement part for it (the cover for the bit you put the tape in is broken), but other than that it works fine. It takes normal cassette tapes, but it records at double speed (better quality) and uses both sides (to get all 4 tracks). This basically means for a 90 minute tape, you get 22.5 minutes of recording time. It's a pretty neat little thing, it's worked for me, and it's good for recording demos and the like, and getting song ideas down. It's only a possibility at the moment - I'd have to archive some masters, and get the replacement part and stuff. But, if you were interested, I would sell it to ya for well under $150 I imagine (though you'd have to pay shipping - I'm in the UK).
EDIT #2: With regards to the Hi-Z issue, the Yamaha AW4416 I'm using at the moment has a Hi-Z input - and I haven't really noticed much of a difference with it. The aforementioned MT-50 doesn't have a Hi-Z input, but I've recorded my (passive) bass direct-inject into it loads of times - it sounds fine.
