Mr Bungle - to save a few quid you can pick up 2nd hand CRP-1 's on ebay.co.uk for about £20 to £25.
For any real tight-@rses (as long have they have got an IPAQ or other Pocket PC) you can get an electronic E6B for free/gratis/nowt from
http://www.navbox.nl/navboxce.htm
Mr. W