How much silver did each Philistine lord promise Delilah for Samson's secret?

Answer: 1,100 shekels

Each lord offered eleven hundred shekels (KJV: pieces) of silver if she could discover the source of his great strength.

“The lords of the Philistines went to her and said, “Entice him and find out the source of his great strength and how we can overpower him to tie him up and subdue him. Then each one of us will give you eleven hundred shekels of silver.””— Judges 16:5 (BSB)