David told Ornan that he would buy his threshing floor for the full (vs discounted) price because he would not offer to the Lord anything that cost him nothing (1 Chron 21:24). An offering to the Lord must be “felt” by the flesh if it is to have any value.
The Lord tells us our very lives are to be a living sacrifice unto Him (Romans 12:1-2). Truly, a reasonable sacrifice on our part!