Garmin os gb discoverer maps... Cheap?
Hi, I'm looking to buy the Garmin OS discoverer 1:50k GB maps but they're £100+. I've found a site which sells them for £20. http://www.ioffer.com/i/garmin-gb-discoverer-1-50k-full-coverage-127349741
Has anyone ever bought any maps from this site or a similar site? Usually if things sound too good to be true they usually are but I thought it was worth an ask!
Alternatively, has anyone else used any cheap sites?