Cheap colour portable plotter
For anyone on a budget, a cheap colour plotter can be acquired by buying a Garmin street pilot iii off ebay. It's an automotive application but carries the same chip as many marine chartplotters.
I'd always been told that this unit wouldn't take the detail on the garmin marine chip but after trying it, it does although not in the detail that a dedicated marine unit such as the Garmin 276c (best portable plotter ever made).
Street pilots typically sell on ebay for £20-35. The chip is the same one that fits in many Garmin chartplotters
The blank marine chips alone sell on Ebay for £25-35. Most street pilots are for sale with chip included.
I recently bought a street pilot for £27. The chip was 256mb (normally 128mb) and also included was a Garmin chip reader(£30) plus loads of Garmin software.