It happens sometimes on our explorations off the beaten track that participants find archaeological artefacts themselves by coincidence, or people in the local communities we visit offer such objects for sale. Other participants may bring archaeological artefacts that they have found, bought or otherwise acquired during their stay in Mexico with them to our anthropologists or archaeologists and ask for a commercial valuation of them. When this occurs, it is an unpleasant situation for all of us, and we therefore would like to say right away that we are not under any circumstances providing such information. If such objects are found during our exploration, and we are able to identify them, we may give an opinion on their age or significance, but that's it.

It is forbidden by law to sell antiquities or to take them out of the country. It is also a serious crime according to Mexican and International Law to excavate an archaeological site on your own without appropriate permissions from the National Institute of History and Anthropology (INAH). This is the case even if you decided to dig for antiquities in your own garden. If you find an object by coincidence, please hand it in to an appropriate instance, a local museum or the local INAH department. If possible, you should leave it exactly where you found it. When such objects are removed from their site of origin, and end up in a private collection without any documentation about the context in which it was found, it is a loss for science, and a loss for humanity.

It is almost impossible for a private collector to have a legal collection of pre-Hispanic Mexican artefacts. Some artefacts that were brought home by the Spanish conquistadors in the 16th century entered European markets and found their ways into private collections and museums. If you possess one of these objects, it is technically legal (even though few 16th century Spaniards obtained the exotic and often valuable artefacts that they sent home in a way that we would consider morally acceptable today...). Almost all other pre-Hispanic Mesoamerican objects that can be found in private collections today are looted, or were excavated illegally and left Mexico illegally. That also is the case for exotic items that your great-great grandfather may have brought home from a trip to Mexico in the 19th century or so...

From the “Principles of Archaeological Ethics” of the Society for American Archaeology:

"Principle No. 3: Commercialization.  The Society for American Archaeology has long recognized that the buying and selling of objects out of archaeological context is contributing to the destruction of the archaeological record on the American continents and around the world. The commercialization of archaeological objects—their use as commodities to be exploited for personal enjoyment or profit—results in the destruction of archaeological sites and of contextual information that is essential to understanding the archaeological record. Archaeologists should therefore carefully weigh the benefits to scholarship of a project against the costs of potentially enhancing the commercial value of archaeological objects. Whenever possible they should discourage, and should themselves avoid, activities that enhance the commercial value of archaeological objects, especially objects that are not curated in public institutions, or readily available for scientific study, public interpretation, and display.”