Befuddled

I've posted previously about being honest when you deal with prospective customers. When a customer describes a scenario to me that I know my company's product isn't a good fit for, I state that. The last thing I want is for people to think I've lead them on so we can make a sale. People won't want to do repeat business with us, and hurts both my reputation and the company's.

But I've encountered one particular scenario that I just can't wrap my head around. I was speaking with a test manager and his team. They outlined their scenario, and what they'd done with my product so far, and the issues they had encountered. I listened carefully, and based on what they wanted to achieve, I knew my app wasn't a good fit. I told them this, and stated my reasons why. Several of the team members voiced their agreement. And then the manager said something that flat out stunned me.

"I think we can make it work. We'll buy it."

I couldn't think of anything to say other than restate my previous concerns. The manager told me that his team would deal with it, and that they would purchase.

How would you handle this?