maximum payload to the moon

I dont know a great deal about space and current rocket technology,
but im Learning (in a very amature fashion!), but i have been trying
to find out about the following.

1) Using current technology and taking into account theretical limits,
what is the maximum payload that could be landed on the moon and what
would be the cost in doing so? Would this cost be lower if 2 or 3
such landings were to be made?