Sorry to add my 2 cents, but may be you need to consider how it will increase the value of the land vs just the value of the contract. Since the billboard is owned by the company and can be taken down, I would personally take no money at all for a period of time if the contract states that you own the structure and they cannot take it down even if they cancel the contract. Now this increases the value of the land which you can easily resale. Also I have seen billboards that are positioned that your land is no longer very useful for anything else, so I would make sure they position it so you can add additional value, like building out the land with driveway, etc. Another point is that I have seen contracts that billboard companies pay all taxes on the lot, so if you increase the value and increase it even more down the line, they are on the hook for the taxes. Again just my 2 cents because the land with real property on it...like a billboard that is real value. In addition if your land allows to build a structure, usually local billboards (of the business at the location) do not require any special license, but because it will be right next to a big national billboard, it will get a lot more visibility, this increases your land and rental for that space exponentially....now that is money in the bank.