This is such a variable as it really does depend on whether you are talking about just for eating or 'shopping' too.

This is just a personal view but we have never got into the big shopping thing in Florida - so have never spent large amounts of money on stuff that in my own personal experience can often be found for the same or similar prices at home if you know where to look.

Meals and shopping for food can be as expensive or as cheap as you want to make it. Eating out can be cheap too eg $5.99 pp all you can eat Pizza buffets in Ci Cis and some very good value breakfast in the likes of Denny's/Ponderosa. For a great value Chinese try Panda Express (way better IMHO than some of the rather seedy/dodgy looking 'all you can eat' Chinese buffet set ups you will see)

Eating in the parks can be expensive but we noticed some pretty 'good dining deals' in Disney this year but you say you aren't going there and I'm not sure if Universal do them (somebody in here will though).

As you are in a villa if you want to keep the cost down - suggest breakfast in the villa (we did OJ/coffee/toasted bagles/yoghurt/fruit at the side of our pool most days - very civilised).

As dsv77 says if you are looking at purely meals only $200- $250 per day should easily cover it - if you and/or the kids want to go 'mad in the malls' and/or discount stores, well I'm afraid you are only limited by how much weight you can bring home and how much UK customs allow - something else people often forget about.