[EricH]

Speaking from experience:

If you know what all the parts ARE, it's not that hard to maintain a Prusa Mendel. It'll need some fiddling here and there from time to time, particularly if it's moved from place to place. (If you need to move it a lot, invest in a cart--a solidly-built one, at that.) Mostly it'd be minor stuff--maybe rebending some metal here or there, or releveling the table (the ones I'm familiar with have a non-standard table, for a Prusa).

Also, once you have one, your first set of prints should be for another one. Why? If you can build a second one, you can maintain both of them.

Incidentally, if neither of you have instructions, or they don't come with your kits, I wrote a set a couple years back that's similar to the ones on the RepRap site but have CAD exploded views and some tips on assembly. If I can find it (which I'm pretty sure I can).