[EricH]

Resistors, especially in bulk, cost very little. My college's EE department has a rack of reels of resistors (not sure of wattage)--if a student needs one (or 12, or a few hundred for, say, 50 identical units) for a project, they go up there, take off the appropriate number, and go use them.

Figure out how much resistance you'll need, get a reel in that size, and you'll be set for "quite a few" signs.