Russia - Kotelnich
This is the only excavation in my list where participation actually costs money.
A week at the dig costs about 100 Euro or 100 US Dollar. The Russian scientists
use all the money to run the dig and you are usually asked to buy badly needed
equipment (drills, chisels, etc.) in your home country and bring it along for
the dig. I believe this is a fair deal, because all your money helps to cover
the costs of an unique dig.
You can be picked up at the airport in Moscow and they will join you during the journey with the Transcyberian Railway to the excavation site some 1000 km away. The dig is in Permian sediments and concentrates on well-preserved mammal-like reptiles (therapsids). Most of the finds are beautiful articulated skeletons.