Hi John, these are good questions.
A good realtor will have the numbers you are asking for, this is why you should look for one who specializes in the area you are considering. They know the local builders, the developments and the market. If you are wanting to buy in a community, you might want to look into contract a realtor as a buyer's broker, so that you aren't just relying on the sales agents and developers for information.
For doing research on your own, there are several agencies that do have some numbers that could interest you.
http://www.construccion.co.cr/ Is the association of builders in Costa Rica. They have on their site statistics related to how many square meters of construction go up each quarter. [urlhttp://www.construccion.co.cr/servicios/edificaciones.php]http://www.construccion.co.cr/servicios/edificaciones.php[/url]
Another site could be the architects association
http://www.cfia.or.cr/ They had a PDF available of statistics for 2005 and 2006.
http://www.cfia.or.cr/estadisticas.htm Another option is the INVU - which is where plans are approved. The web site didn't offer information, but it is possible that by going there you can get statistics on CD. Ubicación: antiguo edificio de la Aduana, contiguo Iglesia Santa Teresita
Now you are right that true comparative statistics are not readily available. In some places city government do evaluate regularly the property values and you could get guidelines there by making the right contacts. You might or might not get cooperation from the city office that approves plans to in order to find out about projects that have been approved.
Now for your other question, the market in Costa Rica is very localized. In my opinion, you won't find that the whole market drops out. You can have slow times in a particular area and a hot market in another. We saw this 2 years ago when Escazú was slow but Santa Ana was smoking hot. At the same time Tamarindo and Flamingo were exploding.
I believe that the US market boom was driven by other factors and you can't say that since there is or will be a bust there that the same thing will happen in Costa Rica. In my opinion, the factors that have driven the market in Costa Rica are quite often related to improvements in the infrastructure. This was very clear in Guanacaste, for example you had new schools opening, the international airport opening, broadband Internet coming and also several golf courses. In the Tamarindo and Flamingo areas you reached a critical mass, where you had enough residents and tourists to sustain a wide variety of restaurants, shops and other services.
Also, what many investors and developers are preparing for is the retirement of the baby boomers. Many will be purchasing vacation homes, second homes and retirement places as they begin to retire. Since Costa Rica is (and should continue to be) an attractive option for those retiring most industry insiders believe that a small (or not so small) will look hard at options outside the US. If Panama, Nicaragua and Costa Rica continue the positive trends that have put them on the boomer's radar, then the entire area is positioned as a solid option to Florida and California.