if you can get it without an ADM at the moment, that'd be a stellar deal. the car is a blast to drive.
realistically, if you don't plan on owning the car for that long (3-5 years) then no, you shouldn't pay an ADM, and you should wait.
if you have plans of long term ownership though, it becomes a bit more murky. someone who pays $5000 more than you over a 10 year period, that's $500 a year, and not a big deal, especially when you consider people are out there who swap cars like candy, if we want to talk about bad ways to spend money, that's worse than a ADM.
anyway, at the end of the day, if you have designs after the car, go check it out, if the lowest price they offer isn't as low as you want, then walk. it's still a rare opportunity to even have a chance at it, so see if you can get it for what you want.