Sadly that's Britain for you, mate. Where everything is twice as expensive as everywhere else.

Plus we're obviously in the run up to Christmas so I'm assuming prices are a shade higher than usual. GB Pockets seem to be going for around £10 and the old brick GBs are more in the region of £15, whereas you're looking at about £20 and £30 respectively if they're boxed. I don't mind paying £15 provided it's in good condition and works 100% - an awful lot of them seem to have dead pixels and/or scratches to the screen, which I suppose is to be expected for a 20 year old console, but still something I'd rather pay a little extra to avoid.