There has been several purchasing related threads running in the Tiffin section of this website. I suggest you read those first. I'll be happy to give you a few tips, however.
1. Get a current price sheet - this one has been compiled by a board member here: 2016 Tiffin Pricing
2. You should be able to get at least 25% off MSRP and up to 28% is not that uncommon.
3. Don't be afraid to place a factory order for a new one. You get what you want, and it is more profitable for the dealer as it doesn't hit his floorplan loan, and you get your 25% off. Downside, 8-10 weeks for delivery.
4. If you have a trade, don't discuss it until after you have a firm cash price for the unit. And don't fall for dealer addons (paint protection for example).
5. If you don't mind travelling a bit, there are some Tiffin dealers who are just easier to deal with than others: Sherman RV, Sherman, MS; Davis Motorhomes, Memphis, TN; and Martin Ingram RV, Birmingham, AL.