So I finalized my deal yesterday after some shenanigans at greenway in Orlando. The dealer who had the truck on the lot would not release the truck to greenway, even after greenway "sold me the truck" and promised they could get it to me, i figured out where the truck was in Orlando, and they gave me a better deal anyways.
MSRP was $65,800 and i got the truck for $54,900 so $10,900 in dealer negotiation. (closed the deal 7/16). The kicker was that they gave me $44,000 for my GMC, which the other dealer was only giving me $40. KBB and NADA were both at $37-41k. I had offers on it at $37k from Napleton, $39k from Philips, and the $40k from greenway. So a lot of my deal was the additional $4000 on my trade and tax on my trade as well. I had a good amount of equity in the GMC too, so my balance was not terribly different. I feel like I spent an extra 3-4k over what I could ultimately get in September, but the problem was my trade value. I have a couple of long towing trips coming up, and my $7500 mile Sierra would have drastically reduced in value in the next couple of months, so I had to take that trade number (i purchased it last year for $46,000 +TTL new).
Anyhow, this truck is LIGHTYEARS ahead of the 2018 Sierras, my wife could not believe it when i brought it home how much newer it felt, and how many more amenities it has. I felt like I made out well, even though it was pretty gut-wrenching to miss out on June deals.