If the Internet prices are higher than the $9999 that the dealer wants, that tells me that he is low-balling the price to get you in and putting the profit in the bogus $2600 dealer prep fee.
Look at the accessories: Screen room $500, WD hitch $500, brake controller $150, Cover $500, so he is charging you $3500 for $1750 in accessories.
When you complained about the prep fee and he waived that, basically just put the profit in the accessories. Betcha he won't sell that TT at $9999 with no prep fee.
Honestly the $13500 for the TT and accessories doesn't sound too bad. If you back out the $1750 cost on the accessories, that's $11,750 on the TT, probably what you found it online for.
No kidding he was overpriced on the first pass, but I think he was right where he should have been when you walked out. Will be telling to see if he stands firm when you go back or if he puts more on the table.
Makes me laugh that everybody wants to buy at cost, the dealer isn't allowed to make any money, or maybe a small amount, but comes time for service these same folks are complaining that it's a 3 week wait to get an appt. because the dealer doesn't have enough techs....cause he can't afford to hire another one.