We are regular guests, and I work at the
Disney Store, so we spend very little. As another poster said "only things that are only available at WDW".
On my last trip I bought...
2 pair costume jewelry earrings--the Disney Store no longer carries them. About $15
1 blown glass manatee at Arribus Bros. About $10
1 WDW exclusive watch, limited edition numbered. (I collect these) About $80
1 Original artwork of Chernabog as a birthday gift to our son. (His fav Disney character.) Don't recall, around $200
1 Make Your Own Park Music CD Around $20
About $10 misc. purchases in the Company D Store (Cast members only) I bought a few luggage tags, a plastic cup for water for my desk at my "other" job, and a Team Disney umbrella.
This was a LOT for us though. The trip before that I think we came home with 2 golf shirts for hubby (both on sale for under $15/each), an autograph book for my neice to use on an upcoming trip that we picked up at Belz for $1, and a Chernabog photo frame ~$3.
I guess a lot depends on what you are planning to buy. T-shirts run $12-40, sweatshirts run $18-100. Snowglobes are generally $60-100.
I would definitely look through your local Disney Store before you leave, often they have much of the same merchandise, and it's about 20% cheaper!! Plus your Disney Club card isn't valid in most WDW stores.
Anne