across the pond it costs around £20,000-£30,000. Is there a reason for the massive price difference?
Be carefull, some of the schools in question are...how shall we put it...somewhat forgetfull in mentioning all of the expenses.

Hence the use of the word "hidden" cost.
Don't just simply stare at the price, analyze the packages they offer.
You may be able to get an instrument rating in a C150/C152 but flying around with just one radio and VOR will not do wonders for your skills if you are looking to go career.
The equipment becomes important.
The more serious schools in the US can get you a combined FAA & JAA, so fully US and European certified for 70K Euro.
For the price of what training in Europe would cost you, you get both sets of ratings/certificates.