Navman iCN320 GPS navigation - £129 or less delivered from ebuyer.com
EDIT: Now just £99 inc delivery
Go through Quidco for 1.5% cashback.
Designed with simplicity in mind, the iCN 320 has a user-friendly interface, is easy to install and ready to drive away straight out of the box.
Features: Post Code input, Portable & user friendly, Door-to-door navigation, Voice-guided directions, Rechargeable battery. 2.7inch colour landscape TFT screen displays bright coloured maps that can be easily read whatever the conditions. The lightweight GPS will also guide you by foot through busy city streets to your destination. The ICN320 is pre-loaded with points of interest to include Airports, Hotels, Golf clubs etc. High sound quality speaker, multi-directional GPS antenna accurate to 5 metres.