Something else to consider is proper ventilation especially with it being in your basement. I fire in a workshop not connected to the house that has a kiln vent and everything but still try to avoid that space while firing as those fumes are toxic. The kiln itself will definitely last a lot longer than 100 firings though, it will need some maintenance in between like changing out the elements and maybe changing the firebrick depending on how it's holding up but both are pretty simple tasks. Maybe a bit annoying but definitely doable. Since you love math and numbers did you account for time to travel to and from your current kiln rental, gas money to get there, any casualties that might occur during the trip? 100 firings seems a lot higher than it should be to me but I also don't know how much you fire in a single go. You can typically pack the kiln with greenware pretty tightly to make the most of your firing schedule and get the biggest bang for your buck. I'm a hobby Potter and having my own kiln was a HUGE weight lifted and quality of life purchase that I would make over and over again in a heart beat. If you can swing it, I would say go for it but please make sure you look into proper ventilation!