I had front pads and disks fitted for around 180 quid. Watch out on the front disks as there are 3 different versions and the only way to tell which you need is to measure the old ones! Also the price varies for each type -nice. Personnaly it was easier for my local tyre specialist to buy and fit the brakes, rather than messing around with mail order. It was all done in about an hour.
I recently changed the front pads on my 96 GTV lusso. They were €50 from an Alfa Romeo dealer. As there are a couple of different types, have the chassis number to hand when buying them. Replacement of the pads is straightforward enough but one thing to look out for is You will need a strong 7mm allen key to undo the caliper.
Havent done the rear's yet but I will be soon. I'll let You know how it goes and how much they cost.