RAM for ibook in UK?

[Daniel Rubinstein]

Hello list,
I want to buy 512 RAM module for my girlfriend's G3 900 ibook. At the 
moment she has the factory installed 128. My question is can it be 
done? and what is the best place to buy the memory online if we are in 
London UK? Apple store wants £190 for it which is a bit much i think. 
If any one has experience with buying RAM in UK, help greatly 
appreciated.

Thanks,

Daniel