I wouldn't indeed... But the bread thing has got to do with way more things, like local costs of grain, personell and all other kinds of bakery costs.
AFAIK, all those iMacs are made in the same factory (or few factories), with the same costs of materials, so that 40% difference has got to be some other reason.
And for as far as I checked, ALL non-US prices (except for Canada perhaps) are quite a lot higher (with the EU as maximum - even in Japan they cost 200 dollars more), and I really doubt that all the money in that percentage is for costs like transport, customs etc.