For the sake of others who may not know - Bob at Pro Products is indeed fantastic, and all of my RHPs came from him. The reason that you can't just go to his website and click on an RHP to buy is that he wants to be 100% sure you are getting the right RHP. So, as mentioned above, his site explains that in order to get an RHP, you first need to send him an email and answer a list of questions he provides, ranging from the species of snake you are keeping to the type and size of enclosure, ambient temps in the snake room, etc. Based on that he'll contact you with information about which RHP to order, and how to order it.
It may seem like an odd system, but there is a reason his RHPs are considered to be the best in the business.