R P.
Even though timeshares are considered real estate, in a sense, they are not in the realm of traditional real estate. When you buy a timeshare from a developer you are paying for marketing costs, salespeople, food/drink, lawyers, accountants, closers, a profit for the developer etc. When you sign on the dotted line your timeshare purchase immediately depreciates much like a new car in 99.9 % of cases. There are some very highend timeshares that may hold their value, but the numbers are few.
As far as resales go, the market (buyer) sets the market price with the following criteria - supply and demand, popularity of the resort, season color designation and other factors. In other words there's nothing set in stone of what your timeshare may be worth ... it's up to the buyer.
Timeshares are not a financial investment (no matter what a timeshare salesperson may have told you), however they ARE an investment in future vacations for you and your family at nice resorts and condos.