GGB now run via the shop4parts site, and ALfa/fiat specialist. Many parts are genuine too, and all dead cheap. Excellent service as well. Also try EB spares (simnpler outfit, no transactional site, but v good service) as well as AO shop.
Their website went a bit mad on me when I was trying to order. Said I had 3 things in my basket but would only show one, and if I tried updating the quantaties it just crashed. Phoned them up and ordered over the phone instead.