As a griddle owner who paid about $900 for the unit itself (Pit Boss Ultimate, though if it had been out at the time Id have gotten the Traeger one as it seems to have the most even heat and other features I like), your cost estimates are ludicrous.
Oil is dirt cheap at Costco / Sams, and you get good deals on butter there as well. When I use mine, I put down a layer of avocado oil, then melt butter from a stick until I have enough.
Thats an absurd amount of sauce, so you should stop wasting sauce. You dont really need sauce for most dishes anyway.
Buying a couple propane tanks is expensive these days, but getting them refilled is dirt cheap, should cost about $20 to refill 2 or 3 tanks, and a tank might last you months depending on how often you use it.
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