We've just got back (well 2 weeks ago!) from a 4 day New York trip & 8 Day WDW trip.
I still ahve $133 on my Fair FX card, BF has $0!
We didn't have a 'budget' per say I took $500 in cash, and $2200 on the card, BF took $400 cash and $1000 on his card (it was my present to him so i footed most of the bills).
In New York we literally didn't even question the cost of anything, even when I bought 4 white wine spritzers for the girls at $58, I'd have died if I'd had spent that here in the UK! I also paid for my friend who we were staying with dinner a few nights as a thank you.
In Disney world we had the Free
DDP, and it was way more food then we needed. We didn't buy any extra food apart from some sweets on the last day as presents for our friends. On days we were at Seaworld/Universal we went to Earl of sandwich the night before and used our QS credits, put them in the fridge overnight and took them as a packed lunch the next day!
We did however go a litle bit overbaord in the outlets, and of course paid for our tickets at Universal and I spent a fortune in the Harry Potter shop
I do think though if we hadn't have bought anything from all the shops (I got 3 t-shirts alone from Disney

) We could have coped on $50 a day between us being on the DDP which would have been for the tips and our drinks. Not on the DDP I think we averaged $100-$160 bill for the TS meals at night (we drink wine by the bottle

) plus tip, then QS meals we would not have got a pudding etc and probably could have shared a meal to be honest.
We also could have been sensible and have used the snack credits for sweets as presents, but that msotly went on treats for us.
I think it can be as cheap as you want or as expensive as your budget allows. On the day we went to Epcot for example, we had a drink in every 'Country' which worked out expensive, 2 tiny glasses of pink champagne in France cost $30
We know we wont be going back until we have kids so we really didn't hold back on anything which was nice, but I certainly wouldn't do that on any other holiday!