affordable double din navigation?

I did purchase the jenson dvd with 7 inch screen single din.  # vm9313 It has a nav reciever that you can add to it.  I now that there stuff is usually cheesy, but I thought I would give them a try and I have had the unit now for about two years and it works terrific, I did not opt for the nav part though, I use garmin.  I did go through four of the cheaper generic ones (such as dual and valor) before I bought this one though.  Just thought I would throw in my two cents.