I have a small area of ground which I have rented out for a number of years. This land has been used to run a business on, not for agricultural purposes. The tenant has asked me about the possibility of purchasing the land. I'm wondering if there is a rule of thumb or suchlike for how many years rental value the sale price should be based on. I know there is no 'correct answer' to the question of land value, but it would be good to have a starting point for negotiations. Any ideas?