With respect to the CPO prices going up and down, one has to assume that there is a constant stream of new buyers entering the market looking at CPOs, who have not seen any of the previous lower pricing, so to them, it's just "the price."
And Tesla might be experimenting with price elasticity to gauge how demand increases or decreases with specific changes in price. With nearly 500 CPOs car in inventory, it makes it possible to do this kind of experimenting to maximize pricing (profit) without sacrificing demand.
As a side story, my cousin is a musician who writes and performs songs for kids. She's really good at it and has a couple of CDs released. She does kids birthday parties, but she absolutely HATES doing them, but there was a lot of 'word of mouth' for her in the community. So in order to do less parties, she doubled her price, thinking 'nobody is going to pay me double'.... guess what? The demand for her WENT UP. So she tripled the price, and still, people were requesting her. I think the last step was 4x her original fee, and still had plenty of demand, so at that point, no matter how much she hates it, she'd doing it because the money in it is so good, she really can't turn it down.
So the same sort of thing might be at work here -- some CPO buyers (of course not all, or even most buyers) might be insensitive to the actual price, but still want to buy used. Perhaps Tesla is trying to capture these buyers and squeak out a little more profit, so seeing cycles of increasing and then decreasing prices is a methodology to do that.
