Mangoletsi why is that not a surprise, they used to be very good and highly regarded but sadly not any more.
My concern would be how would an independent warranty stand up if there was a gearbox problem and you bought the Brera having been told this.
I'm with Peter RM if it starts off badly it can only get worse with a dealer, I bought mine trade but not from an Alfa dealer, I was told it had a faulty wheel bearing that was replaced two week after I bought mine at the traders cost, I didn't even notice the problem on the test drive or the following two weeks of ownership.
My thoughts are, you've found what you like at the price you like and it may be too good to be true.
Alfa's are love or hate cars if you get a good one, you'll love it
If you get a bad one you end up having to persevere and unless you are a true enthusiast it will put you off Alfa Romeos for life
My first GTV was a dog but I went in blind, but I was still hooked