Even if you use it to mean "have in mind," the passive contruction of "to be bought" is odd in this context.
"Do you have anything to buy?" might possibly be said, but the meaning doesn't fit the context here, where the buyer is not even going to the store.
If we want to express this thought, I think we'd say:
"I'm going to the supermarket. Do you want me to get you anything?"
- Is there anything I can get for you?
- Do you want me to pick anything up for you?
- Can I bring something back for you?
- Do you need anything?
- Do you want anything?