I was thinking the same.....
Aside from money for food/drinks, I'm thinking of taking around £250 for 5 days?
I guess it depends on what your weakness is, shopping wise?

Is it clothing? ornaments? toys? outfits etc?
I'd like to treat myself to just one nice Disney hoody or t-shirt out there, i'm not really into ornaments etc but that was before I had a child, now i'm more sentimental and love reminders of things....but i'd be happy with a Disney pen to be honest! lol
My daughter is 4 and like every other 4 year old, obsessed with teddies!
I have already promised her a Bolt one! (just hope to goodness they still sell them when we go in May)
I am taking her Elsa dress with me but fear I will spoiling her a little each day, but they do say life is short so as long as I don't go too mad, who cares!?

I will however, without a DOUBT.....be purchasing Mickey ears for me and my daughter! haha!!