How to nicely close a business letter? Help!?

Question

I emailed a business to buy a product, however they did not have the type which I wanted. How do I say "thanks for responding, but that's not what I wanted" in a nice way?

This is all I have in the email:

Hello again.

Actually, we were only interested in purchasing bio-diesel blends of B20 and lower.

Now, I can't think of anything else to write? Do I just close it with a best regards? Or say thanks for responding? Or say they had good prices? (I am new at this)

Answer 1

"don't write to me again"

that was a joke

Answer 2

I do appreciate your timely response and am looking forward to opportunities to do business with your firm in the future.

Sincerely,

_______________

Answer 3

"Thank you for your efforts to assist with my request.  I hope we will have a successful outcome in any future purchase attempts."