Was loking on Hmv to see if they had any decent games that weren't too expensive and saw that they had a 2 for £25 offer running. It appears to include games in all formats which can be mixed.
There appear to be a lot of wii and DS games aimed at younger players such as Cars, Bratz, Mater National, Carnival etc so at £12.50 each it doesn't matter as much if they're not that great.
Obviously there will be some games that can still be found cheaper elsewhere, so check find-dvd first, but it does look like ther might be a few good buys!
I did a search and couldn't find this already posted, but if it has been I'll apologise in advance!!!
Stated price for 2 games. Link to the first page of included games in all formats.