I am looking to purchase a Model X and came across two interesting choices available with Tesla and was wondering how do I calculate whether it is a good deal or not? I did go through tons of posting on how to calculate the price, like subtract the tax credit, $1 per every mile, $10,000 per year, etc. but the X's I am interested in are with Tesla and have been previously demo cars. Is there is a way to calculate a reasonable price for them too or do I have to go with the offered price. Any response will be appreciated. Here are the two that I like: Model X 75D 5YJXCAE20HF041764 | Tesla Model X 90D 5YJXCBE21HF044694 | Tesla Thanks!