Still a great deal. Elements are basically considered a consumable. Though they can last for years (depending on use, too, of course), things happen, and they will eventually need replaced. If you download the wiring diagram for your kiln on Paragon's website, it gives you a part number. Looks like replacement elements for that kiln are around $120, which isn't terrible.
As for the controller, those can last for decades without ever needing replaced. If it does crap out, I'm sure Paragon would sell you a new one, though you could get any number of controllers to work for it. Evenheat makes a nice touch screen controller that coud probably be adapted to this kiln pretty easily. As count said, Auberins sells some quality PIDs for good prices as well. You'd probably have to modify the front mounting plate, but most PIDs should wire in just about the same, as long as the input voltage range is OK.
What may burn out before the controller, however, are the switching relays for the element, or possibly the control transformer. These are relatively cheap, and commonly avaible from any number of suppliers.
At any rate, if it wires up and works now, you may be good to go for years and years... If this is something you rely on for income, it's still not a bad idea to have an extra element or two on hand, along with things like fuses, a relay or two, and even a transformer. A spare controller would be a low priority as far as I'm concerned, but you could always have a spare to adapt to something like a salt pot, tempering oven, or who knows what.
