From my "prehistoric" days when self-cleaning ovens didn't exist, I always
used a sheet of aluminum foil on the bottom, especially when I cooked foods
that could boil over or leak onto the oven floor. Dispite all the stories
that the aluminum foil would mess up the baking, I never had any problems
with my baked goods. You could also try a large cookie sheet or two that
fit under whatever was in the oven.
It's always easier to wipe out the oven after each use. Any spills can
(usually) be removed with a baking soda paste and some elbow grease.
Personally, if it were me, I'd just use the oven to death and then watch
for some really good sales with good financing deals. I (personally)
wouldn't put money into a 10 year old stove ... you never know when
something else might give out.
Ilene