I applaud you for doing your research before having an animal like this but I have to warn you against it. As a keeper who has kept special need animals, its a pain in the A$$. Its going to be hard and difficult to care for these guys. I always recommend to step aside and wait until you are sure their requirements are met.
1. Such as, will there be a constant food source available?
2. Will you be able to keep such a large cage for such a large animal. Since they are semi aquatic, they are going to be messy. I kept a water monitor here for a month, he was a 5 footer and I gotta tell yah, never again. I was just bordering the guy but I will say Monitor water is nasty especially since they loved living in it. So a high end large filter is a must. I would recommend 2 or 3 for the setup.
3. you say you are not ever going to rehome them but what happens if you are struck ill, and can no longer care for your pet. Heck, I have a 14 foot burmese python here, and I am technically the 4th owner. It was my ex's pet and when she left I got stuck holding the snake. She got it from a man who had throat cancer. he could no longer keep the snake (he got it from the herp society as an unwanted pet), so the snake came to my ex after that.
So there is a lot to think about, rare animals in the herp trade are that way for a reason. I just want you to step back and just think about these animals before you drop around a grand each for the lizards.