I have an old scanner that I would like to use with a PC, this is to replace my even older parrallel port version!

Trouble is I am missing the 12V 1.25A power supply. Looking around they seem quite steep (considering that they come as standard on £5 appliances). I saw this one for £10:

Ebay power supply

Is this about the going rate and how can I be sure the male end that will go into the scanner will be the right diameter?

Any ideas appreciated.