Warming spot? I don't think an iguana with a PhD would figure it out. They eat, bask and move on. At night they want to be in a tree.
You get a discount when you go to the vet but what if you have over 2000 igs? According to the Department of Florida Fish and Wildlife, freezing is considered humane. Vets had done this years ago with small reptiles and was endorsed by the AVMA.
The MOST humane way of freezing is to slowly chill to lower temperatures. You can refrigerate to the low 30's until they are totally limp, then freeze for 24 hours. That also makes them safe to eat. FYI, the flavor is a cross between crab and chicken. Probably more than most people here want to know.
I think a Florida restaurant might do well serving invasive Florida wildlife like Lion Fish, Python, Iguana and a long list of others.