After looking to buy DS games on Ebay and finding that many are fetching to much I did a little shopping around.

 The most popular games at the moment are Brain Training and the 4in1 Monopoly which are all fetching around £20 including postage, but these games (among others) are £24.99 delivered from Play.com and only £19.99 in Wollworths.

 I would therefore advise that if the game that you are looking for is constantly fetching around £20 with the delivery then you should check out your local Woolworths, Choice or surf to the website Play.com and enter the name of the game you want to find out what it should cost, as even a game that costs £24.99 brand new must be better than buying a used one for around £20.