I’d like to think a used SO4 in good condition is worth only a bit less than list less the cost of a Maintenance Kit.
What would you like to make with it which is awkward to do using traditional woodworking techniques?
What designs have you had difficulty working up?
Drawing in Carbide Create isn’t that much different from drawing w/ a compass and rule and straight-edge, and erasing is a lot easier (and neater/less messy) — for one example see:
if you’ll post a design which you have difficulty drawing up we’ll gladly walk through it w/ you.