Dependant on your interests, species present and your priorities in the matter, consider offering a split of the venison fee.
If trophy animals are available, and you are happy to shoot with the aim of managing for quality - maybe consider offering a split on any fees brought in by occasional accompanied stalking.
This option will allow you to highlight the benefits of a long-term relationship and the potential for an increasing income for the land-owner. It also gives you the chance to warn him as to the dangers of letting the ground for a lump sum, then having the quality animals shot out while control is not extended to the female population!
Unfortunately, a 'fair' price varies wildly, dependant on locations and species available. Good luck!
Rgds Ian