Public Service Announcement: for any interested buyers, a dealer markup of any amount is just a starting number. Of course they would love the first person contacted to enthusiastically say "Yes! I'll drop everything come right now and happily pay your insane value added fee."
Realistically an entirely appropriate response could be "I'll buy it for MSRP and not a penny more."
They don't have to say yes, but somebody will. If the car sits, they certainly will.
I've had used buying experiences where instead of the sales guy bugging me, I'd reach out to him every couple of days and ask "Do you still have my car? I'll buy it today for $xxx." I had visited, driven the car, met the salesman. Both took a few days (more than a week, maybe about two) before they relented.
It just depends how hot the market is, and how badly they want to move that particular vehicle. It seems that supply has increased enough where negotiating is once again possible (hard to negotiate when the buyer behind you is willing to pay whatever).