I've got a garmin dezl 560lmt been using it for a while now and its not taken me under a low bridge or unsuitable road yet (touch wood!) Had to turn the traffic rerouting off though as the detour can often be longer than a 10 min traffic jam! Cost about £300 from halfords, free maps for life included, probably cheaper on the internet but I wanted some comeback if it was shit lol! There are some for £60 on eBay but you get what you pay for imo, and £300 compared to a bridge strike is nothing!