Satellite navigation systems are getting cheaper and better, and although an aftermarket unit is never going to be a substitute for a nice, flush manufacturer fitted one, the price of these handheld units makes an absolute mockery of the four-figure sums usually commanded by a maker.
You know the drill on one of these: should I get a Tom Tom, a Garmin, a Navman, a Blaupunkt - or one of a few other, cheaper alternatives? The truth is, they're all pretty good, so it's a case of working out the best balance of price and functionality. We'd say that £100 is a decent budget, enough to get something portable and decent enough to actually pick up a satellite signal or two. We'll stop short of naming our favourite, but when you find one you like, shop around for the best price - there are quite large variations from shop-to-shop. Find one on Yahoo! Cars.