In Leccio, about 25 km from Florence there is The Mall where you can find Gucci, Ferragamo, Valentino, Armani and other famous Italian designers.
You have to take A1 towards Rome and exit at Incisa Valdarno and follow directions to Leccio, The Mall.
Near Florence there is also the outlet designer village in Barberino del Mugello. There are about 100 shops such D&G, Prada, Gucci, Adidas, CK and so on. To get there take the A1 towards Bologna and exit at Barberino del Mugello and follow directions for Barberino Designer Outlet.
Thank you. The only problem with provided link that it's 2 year old. I j=know for fact that roundtrip on bus is 13 euros now. I hope everything else stays the same and mid-August might be good time to do some shopping.