There is a propane/butane fueled toaster oven listed on Amazon for $169. I don't see why this could not be used inside as it doesn't appear to be a whole lot different than the propane oven built in other than it is counter top. However, if is just toast you want, then this should work. I have used one for years for inside and out on gas cooktops.
Stansport Folding Camp Stove Toaster