Then you want to bargain a discount, a faster delivery, a whatever, for being a public reference.

In other words, if they want something, and want it badly, instead of monetizing it with $$, monetize it with a case study.

Personal favor also. You go the extra mile for one user/infleluencer/decision maker in a customer company. Then ask to return the favor: "could you spend 15 minutes talking to this prospect of mine, it would help me a lot".

They can say no, find an excuse. But it will hurt them because they know you helped them unreasonably in the past, it was valuable to them, and you may be less willing to do so in the future.

Some will say yes. You just need one or two.