The ski rental is expensive, and what you would get from rental shop are ... rental skis.
It sounds like your skis have not been used too much - so I would think that they are still in good shape. Since you haven't used them for 9 years, I would recommend that you bring them to a pro shop for a check up of their bindings for safety.
For your kids, they can sign up for learn-to-ski/snowboard package mostly covering their rentals, lift tickets, and lessons. Or you can ask if Seven Springs has something like Kids Mountain Camp that they can sign up.