Up until a few years ago, credit card networks had divisions that were trading on transaction data, but they've had to shut those down. So now they sell the anonymized data to prop trading firms and advertisers. I think cash is your best bet.

Hah, I actually did a small project on some of this data for one of those companies. Pretty amazing what you can get out of 50 char descriptions at scale.

Do you happen to know the law that caused them to stop trading PII? Is it only the networks, as opposed to the issuers who trade information?

Small credit unions would be your best bet, but I'm not aware of any specifics unfortunately.

The problem is small credit unions still use co-branded cards with Visa/MC, etc who sell your data. I believe AMEX is your best bet for privacy, because you are already paying a premium to them, or good ol' cash money.