I found it cheaper just to buy here in the uk, from any shops with special offers

Last year asda had 3 bottles solaire suncream for £10

I find also spuperdrug to be very good with special deals

Puddleduck

You should be able to buy most international brands in Italy but with the £ being at a rock bottom exchange rate most things will seem very expensive. I don't know which airport you are flying from but if there is a Boots in your departure airport airside you could buy extra supplies there as they won't be subject to any weight restrictions. I expect you have already considered this option though.
Have a lovely holiday, it's an interesting part of Italy as yet not spoiled by mass tourism.

Judith

Thanks guys. Funnily enough Judith great minds think alike; we were talking about doing just that this past weekend