I see this every more frequently on Ebay. I suspect that for some things people just don't look up the price beforehand and assume ebay will be cheaper.

(I walked past the shop yesterday, and they were doing a dongle plus 12GB (to be used over max a year) for £99 as a Christmas package, though if you're not at the shed much, it may not be worth it. I am definitely looking forward to having more internet access this Christmas than that snatched on the family computer next to the telephone.)