Until this is confirmed by someone that we know we can trust we'll classify this as rumor, but all indications are that this information comes from a reliable source and frankly it wouldn't come as too much of a surprise.
And here's a Google Translate aided excerpt of the important bit:
Aston Villa has taken the option to purchase Bradley, including the transfer of the loan fee brings one around five million euros.
"Around €5 million" is likely £4.5 million or so and word has it that figure includes the loan fee. Opinions about Bradley's abilities are not shared by all of this website's authors (to say the very least) but in my opinion that's a very decent price tag and I'm firmly behind the move. At the very least Bradley provides depth to a midfield that will be missing Nigel Reo-Coker and if he's able to develop and fulfill his potential it could end up being quite a bargain.