There is no set percentage of the value of the lot. I sold a house 9 months ago on Pistakee Lake for $245,000 and the buyer knocked it down & built a new house. That lot was 100% of the value to that buyer. The major factors that affect the value of lakefront lots are view, water depth, desirability of that particular lake, elevation (& floodplain or wetlands), neighboring homes and width of frontage. Let me know if you'd like more specific input on a particular lot. I live in Fox Lake and have specialized in lakefront sales for 20 years.