Under Czech law, the two hikers may be entitled to a reward of up to 10 percent of the collection’s value.
To be an incentive to turn in found treasure, it should be 50% of market value.
That’s before taxes, fines and fees.
In the UK, anything like this that is found must be declared. However, if it has no historical/museum worth it is returned to the finder. If a museum does want it they have to pay the estimated value. This policy promotes the detectorists to explore. The detectorists if searching on private property need to set up an agreement with the landowner. I have no idea what those percentages might be. 50/50??