You're getting screwed by the GBP exchange rate plunge. (some might say: correction, and having lived in the UK during times of the €1.50 pound, I'd tend to agree) Euro prices have stayed the same. And yes, ordering Apple gear via the UK store or UK Amazon was a bargain for mainland Europeans for a while because Apple only seems to adjust for fluctuations when they update products. Shows you what kind of mark-up they're using to be able to afford to do that. On the plus side, you'll be able to get cheap Apple gear from the continent if the pound picks back up.
Without wishing to belabour the point, the prices for the same unit (the lesser-spec'ed Mac Mini) also seem to have gone up in the Irish and German stores (to pick but two), from €499 to €599.
I just checked amazon.de and you're absolutely right, sorry. For some reason I thought the old minis were €599, too. 166MHz and 40GB more, the nvidia chip, and losing the remote are worth €100? Hmm.
Nevertheless, around 50% of the GBP 392->599 increase is down to correcting for the new exchange rate. Not that that helps you at all.