Purchase price is not the issue, but workability and reliability is...!I've complied a list of GPS's in the range of $399. to $500. and came up with some really nice units, both TT and Garmin, no others...The TT 510 was one that also interested me... But the Garmin 2720 has some things about it I really like.
See below for the details to the Garmin 2720:
WAAS-enabled, 12 parallel channel GPS receiver
3.8" diagonal, WQVGA color, 454x240 pixel, glare-resistant TFT display
touch-screen control
preloaded City Navigator North America NT v7 maps with nearly six million points of interest
turn-by-turn directions
voice prompts and proximity warnings
customizable points of interest
2000 user waypoints
2000-point track log
50-route memory
detour function
custom road preference
auto off-route recalculation
trip computer with odometer, timers, average and maximum speeds
built-in photo sensor
3-D or top down, track-up, north-up views
USB 2.0 interface
built-in patch antenna
MCX-type connector
dash mount
alphanumeric remote control
12V power cable with external speaker
USB cable
AC power adapter
beanbag mount
protective cover
owner's manual
quick-reference guide