The Pioneer AVIC line is very popular - just search 'AVIC' on here and you'll find quite a few threads. Getting NAV, DVD, and iPOD controls in one unit will be pushing the upper end of your budget, especially once you factor in all the little odds and ends you'll have to buy for the install.
FYI, the AVIC Z110bt (top-of-the-line) can be had for $898 right now from
www.6ave.com (after a $200 rebate from Pioneer).
For me, if I'm going to spend $800 and get the second-best model, I always end up spending that extra hundred or two to get the top model.