IMO, a large format printer should be standard in a college theater facility.
If your plots fit on a 24" wide by whatever sheet, you could easily go with the HP
DesignJet 130nr with a built in roll-feeder and cutter, you'd be fine for up to 24" wide. It also has the Mixed-Ink (light cyan and light magenta as a complement to the standard CMYB). We have one of the DesignJets here, and it's absolutely awesome. It works much more often than the plotter, and is consistent in its printing, and doesn't need the print head cleaning that the 10 year old plotter does because it's so much newer.
For 36" printing, the price jumps significantly, and you go to something like
this.
For 42" printing, you go to something like
this. I'm almost positive that this is the one that the TD here has in his office. Very nice plotter.
Funny, that. Getting a 42 inch model and printing on 36 inch paper from it would be cheaper.
Make dead sure that if you get a printer, it can speak Adobe PostScript 3. This is vital to being able to print many plots and any adobe files.
Also, with a plotter, your students could design on the computer as well, as that is how many professionals do it these days. (Notice that I didn't say most, I couldn't find the recent
poll numbers of old geezer lighting designers. No offense to them!)
But, if you really aren't gonna buy, check out the art department if your college has visual art as a major. They will probably have something like the DesignJet over there (our DesignJet is actually an art department discard because they couldn't get it to work, but we could, so it's ours now!).