Well, since most of the continental companies cast in Britain, I can see at least one reason while it is cheaper to do it in UK.
The market dictates the rules. If Freebooter sells its stuff for 12 Euro, good for them.
The math is not that simple - reduce price by half, sell twice as many.
Even if the sales would go up twice, the costs would remain the same not to mention the man power to man (lol) more packaging, shipping. So in the end, business wise it is much more efficient to sell one mini for 12 Euro then 2 for 6 or even 3 for 18