Here is a link to a few customer reviews of a $500 escort units from crutchfield, look at the ratings that gave the units 1-2 stars. These are the real world reviews, not the BS 5 star ones.
Escort Passport 9500ix (Red display) Radar detector with GPS and preloaded camera database at Crutchfield.com
Bottom line do the speed limit and save yourself a lot of money.