Well, for most reptiles minus monitors, 140F would either kill them or do some severe neurological damage that the off gassing would be a moot point. I’ve had a Nile monitor and a couple Savannahs and honestly for a monitor, I would just use 1/2 Inch plywood. You need something like an 8x4 cage and around 2 feet of soil for them to dig in. There is a local guy here who builds cages from pvc and breeds water monitors and he uses plywood as well. Then just stack a bunch of bluestone or slate to create the 150F hot spot with hanging lights. Not sure I would trust pvc to hold the weight of an 8x4x2 flat of dirt. Arboreal monitors would be different but I would think you would be wanting to heat a branch or log and not the floor of the cage. Not exactly sure as I’ve never kept anything like Ackies. But a plywood cage would be easy to make. Just use 1x1 for a frame and nail plywood sheets to it. Then frame in a tempered glass window.
Not trying to discourage you like I said in PMs. Just be ready to answer questions from guys like me who are skeptical to reinvent the wheel lol. Like I said, I run a automotive shop and I always get vendors wanting me to switch to them and how their products are “better”. Yet when I press them to explain what exactly makes their products so much better that I would want to switch my stock etc, they can’t give me a good enough reason.
If you do the same quality as AP in a faster time, I would think you would do fairly well locally. You can also talk to your local reptile shops and see if they would be interested in maybe doing a consignment. That would get you decent advertising and then the local customers could either contact you through business cards left with the reptile store or the reptile store buys them from you and then resells them. Either way it would be a win/win for you.