Thre is some great info on the Lexus website where I'm sure you've been, and yes it is correct there are only 2 additional options for the 400h (and you can only choose one):
1. Mark Levinson sound system & Heated Seats
or
2. Read DVD Ent & Heated Seats
We went with the ML sound system and it is quite nice! I'm not an audiophile, but I do think it's a great sound system.
We payed sticker as well, so it sounds like everything is on the up and up with your dealer.
Congrats on your good fortune in getting one so soon!