Land contracts are useful instruments for sellers who are selling a home and contemplating carrying the financing for a buyer. It gives sellers a built-in income and generally a better interest rate than rates offered on money market accounts or certificates of deposit. However, a prudent seller should take steps to protect equity and ensure the buyer can fulfill the terms of the land contract.
You can also look to certain companies and organizations that have a concentration of people that may fall in the above mentioned roles such as investment companies (i.e. Charles Schwab, Fidelity), financial advising companies (i.e. Morgan Stanley, Merrill Lynch). There may be a higher concentration of people who can both afford and want to build their own custom homes or to build income-producing properties. Try linking yourself to financial advisors who may already know of people who have these types of dreams. This isn't a comprehensive answer of all the possibilities but just some thoughts. Good luck!