What if the original owner wanted to redeem his land?
Leviticus 27:19 (ESV)
19And if he who dedicates the field wishes to redeem it, then he shall add a fifth to its valuation price, and it shall remain his.
If the worshipper wanted to redeem his dedicated land, then he was required to give 20% above the priest's valuation of the field. The point is that the price of redemption was equal to the investment.
19 And if he who dedicates the field wishes to redeem it, then he shall add a fifth to its valuation price, and it shall remain his.