Hey! Well originally I took $1000 AUD spending but by half way I had to get my parents to send me money and I got another $1000 AUD which lasted nicely. It depends on whether you want to buy things as well though, a lot of people bought Clogs and Venetian glasses, clothes and perfume in Paris etc and those purchases can get quite expensive.
Museums and those sorts of things could get expensive, I think the Venice bell tower was $20 AUD and public toilets cost to get into. Apparently to cover maintenance costs. Only like 20-50pence. I hope that helps!