I use my DW about once a year. period! but there are others that expect it, count on it, and would be lost without them.

A used DW from Craigs list is a good idea as long as it works. it doesnt have to be a fancy pot scrubber sanitary rinse thing for a rental, just has to work. A basic run of the mill machine should suit everyones needs.

You may find shopping the sales at stores will net you a better price on a new machine, with a warranty. Haggle! even on sale, I always ask the salesman "is this the best you can do?" shop sites that compares stores for you like Mysimon.com or the like. There is NO need to put a fancy machine into a rental unit.

The more bells and whistles it has, the more things there are to be broken. A simple DW should be fine. I would really think you need to invest in one tho.