A K1000 is definately a better choice for long exposures than anything like an N80 because of the batteries - long exposure here meaning a few minutes or more. Although a K1000 is a great camera (hey, it's what I started on!), how about a Nikon FM so you can use the lenses you already have? You should be able to find a decent used FM for $100 or so, and in features it's pretty similar to the K1000.

One nice thing about the FM and other cameras of that series is that is has a (sort of) mirror lock-up. Once you start the self timer, the first thing that happens is that the mirror locks up. This could be handy too.