1. Clamps can provide a wide range of punishments depending on where you put them, how strong they are, and how long you leave them on.
2. Require her to dress a certain way (or go naked) for a some period of time based on how much she spent. le forgeron had some good suggestions for this one.
3. Make her pose for kinky pictures.
4. Make her beg for something on the list as a bonus.
5. Make her tell you that she is a slut, a whore etc; and that she's your slave, your plaything, her body belongs to you etc. Make her write it down. Maker her post it here on the forum for all to see.
6. Forbid her from having an orgasm while doing someone that would normally cause her to cum.