Dead Or Alive Dimensions is a surprisingly great portable fighting game; even giving SSFIV a run for its money in terms of character balance, visuals and controls. Coolshop are currently charging £16.49, which trumps CD Wow by over six quid.
I don't know how long their stock will last, though.
As portable fighting games go, Dead Or Alive Dimensions isn't bad to look at and it's pretty good fun too. If you're a fan of the series there are plenty of familiar faces to reacquaint yourself with, although you could always check out the new characters to mix things up a little bit. Amazon and The Game Group are parting with copies of the game for £19.98, which'll make you a saving of over £7.50 on the next best offer coming in from Play.