im not gonna say

but it could help
the general consensus is that either the Rykaline 6010 or the BU303 are the most economical models. I got the garmin 16a from a friend who dismantled his carpc when he sold his car and it supposedly has 5hz refresh rate. But i havnt got a chance to put it in the car yet and test it.
as for gps software.
iguidance v2 or mapmonkey Destinater3 are your best bets. I use and like iguidance v2, i couldnt figure out how to load the Destinator maps into the software, although i never put a lot of effort into it.