I always bring at least 1000. (and a credit card, just in case) for souveniers, because I usually buy a ton. I try to buy as much as I can at the outlets, especially when I am bringing stuff home for family and friends. We can usually get something for everyone, and get much nicer things at a much better price when buying at the outlets. At WDW, snowglobes (65-120), tshirts for adults (19)., Mickey ears, beanies, magnets, mugs, postcards, key chains, pens, sweatshirts, pins, Halloween party pins & tshirts, DVDs, CDs, Mr Potato Head, scrapbooking supplies, and Pal Mickey (50) are probably some of the things we will come home with in Oct. At the outlets, I will try to find some of the same, as well as toys & clothes for DD1, a new disney watch, a disney statue or collectible, new disney tote, clothes for me, and souveniers for two older DDs (14 and 10) who will stay home with their dad.
I made a spreadsheet and listed all my meals at DW and how much each would cost. I figured in several character buffets and estimated three meals/day. We probably won't spend as much as I figured, but the total came to about 750 for DH, me, and DD1 (won't have to pay for her) for 10-11 days.
Have fun!