1 Chronicles 21:16-26
  David accepted responsibility for his sin.  1 Chronicles 21:17
  David knew a man named Gad who was a prophet of God.  The angel of the LORD commanded David to build an altar to the LORD on the threshing floor of Ornan the Jebusite. 1 Chronicles 21:18

  David took action because he knew he heard from the LORD through Gad. 
1 Chronicles 21:19

  Meanwhile, Ornan saw the destroying angel and his four sons hid themselves because they saw the angel also.  This father and sons were threshing wheat.
  David approached Ornan.  Ornan prostrated himself before King David, with his face to the ground.  1 Chronicles 21:20-21

  David talked with Ornan and told him why he wanted to buy this threshing floor.  David would build an altar to the LORD there.  And David would pay full price.  David would be obeying the LORD and the plague would be stopped. 
1 Chronicles 21:22

  Ornan was willing to give the threshing floor to David and he offered the sacrifice of burnt offering, his oxen.  He would even throw in the wooden threshing sledge for the wood for the burnt offering and wheat for the grain offerings – Ornan was willing to give it all. 1 Chronicles 21:22-23

  But King David said to Ornan, ‘No, but I will surely buy it for the full price, for I will not take what is yours for the LORD, or offer a burnt offering which costs me nothing.  1 Chronicles 21:24

Consider this  ~

David offered an offering which cost him something.
What are you offering to God, which costs you something?