Nah, Villa will ofter a lot more cash, they are Villa (not little old Brentford) and they'll be joining up with their beloved old boss.
Brentford will play serious hardball on transfer fees though.
Without checking back, it's the first time they've not gone for "a name" though isn't it? If so, it's a different kind of appointment, so maybe they'll allow him the time he may well need.
Look out for the Brentford -> Villa player exodus in January though!