Lag - I use Skydemon and I think it an astonishing piece of software which I would heartily recommend. Tim Dawson and his team have that rare knack of being able to write software that is both a pleasure to use and does the biz. The most cost effective config I think it to buy the PC/mobile version and then synch onto a cheap WinCE enabled GPS device. You can get oriental versions of these devices for about £60 from eBay. I think they offer a trial of 30 days on the software which you can download.