How to Buy Casa Iguana
If you are buying a home or property in Mexico from an expat, that property is held either in a Fideicomiso or a Mexican Corporation. Those are the 2 ways foreigners can hold title to a property along the coastal zones and border areas in Mexico. Casa Iguana is owned via Fideicomiso. The buyer can assume the remaining 41 years on this Fideicomiso. This makes for a less expensive closing for both parties. The seller has a reputable local lawyer (a notario) who specializes in these transactions.
In addition, the seller can offer financing or a rent-to-own option with money down. Financing is very uncommon so this bonus if you're waiting on your own property to sell or have other financial obligations.
A Fideicomiso is a 50-year perpetually renewable and transferable Bank Trust through which foreigners acquire irrevocable and absolute ownership rights to property in Mexico.
This Trust is the legal equivalent for fee-simple ownership and is provided specifically for non-nationals to own coastal and border property. Essentially, it is like a Trust in the United States —the bank holds the legal title to the property, with all rights and privileges of ownership, including exclusive use and enjoyment, held by the Trust beneficiary—you.
You retain the use and control of the property and make all decisions concerning the property. You have the same "bundle of rights" as owning property with fee simple title. You have the right to use and enjoy, lease, improve, mortgage, sell, inherit and will the property.
You can read all about this from an experienced source, here.