I have Lin and Larry Pardey’s book, Cost Conscious Cruiser that has information on hull material choices.
Fiberglass is the most popular material by far, but be able to discern between the well built boat and one that has poor reinforcing and bonding for floors, bulkheads, with cracking and structural failure. Osmosis blisters occur on about a third of the boats, but hull can be sealed. Rotting core materials like end grain balsa, plywood, or foam for stiffening on decks and coach roof can be repaired. Avoid hulls with core materials as hard sailing can cause separation and breakdown of material. Fiberglass can be neglected longer than steel and wood.
Steel is said to be good if the boat hits a reef; however, may a boat has been left on a reef because the damage was extensive enough that re-floating the boat was not worth it. Considerable maintenance is required for steel boats. Eric and Susan Hiscock,
http://en.wikipedia.org/wiki/Eric_Hiscock, who have owned both wood and steel state that it takes two or three times the work to keep a steel boat in good condition than it does a wood boat. Regular inspections for scratches must be done and paint applied. There is also the problem of compass deviation from the steel hull. A remotely mounted electronic compass up the mast helps, but using a hand-bearing compass is not possible for taking sights on landmarks for navigation. Steel rusts from the inside out so damp areas like a marine toilet, refrigerators, chain lockers have to be inspected and repaired. Most marine brokers consider a steel boat more than ten years old as having really low resale value. If you are willing to remove the interior completely and refinish hidden corners, replacing steel plate in some areas, a steel boat could be affordable.
The French have well-built boats of aluminum that are long lasting and low maintenance by not painting the aluminum. The aluminum takes on a battleship gray color. However, dissimilar metals can cause electrolysis. Also electrical system leakage can cause a severe kind corrosion. These boats are custom designed so are more expensive and hold their value. Good deals are hard to find.
Wood has fallen out of favor because it is cheaper to build a production boat using fiberglass. Wood is a good hull material, but most production wood boats are now old and a survey is very important. Also, softwoods such as fir and pine where iron fasteners were used are only good for twenty to thirty years. Wood and epoxy construction in more recent times are sold at low prices because many were home built, and some were done to questionable craftsmanship as were some production boats where boats were not done to a an acceptable design. Also the epoxies that were used were not really waterproof and were also susceptible to weakening when heated to temperatures as low as 120 degrees Fahrenheit. Look for a traditional boat laminated with rot resistant woods like cedar or teak using resorcinol glue that is completely water proof, heat, and fatigue resistant. This glue leaves brownish red joints. For any wood boat, bronze or copper fastenings must be used and three coatings of creosote to any bare wood that will be underwater is needed to control teredo worms. Paint is then applied to the creosote treated wood.
Ferrocement hulls are mostly built by amateurs and are difficult to ensure. Poor quality cement and questionable placement of rebar are issues. Maintenance is as difficult as steel and puncture resistance is low. Resale value is very low; however, some have gone cruising for little money. Some are commercially built and are usually of better quality.