When you try to buy something there are a number of costs. Obviously the large bulk cost directly from the manufacturer is the cheapest per unit, and as you scale down the cost per unit normally increase significantly.

In the case of transporting stuff to the moon, you have to ask how much does it weigh and also what volume does it take up. You also have to ask when do you need it, and can it be slow transported through the radiation zones.

There has been so little transported to the moon and over such a long time period, I don't think there is a current price. I think you would have to just detail your requirments, put out a bid, and wait for the responses.

There are a number of entities competing for the ($30M) Google prize to put a payload with a specific capability on the lunar service. Some of these entities hope to prove technologies to compete with large space organizations in their ability to deliver payload to the moon.

Bottom line is the cost is very much in flux and subject to so many variables that it really can't be tied to a number at the current time.

I did find one reference that seems to give a pretty good overview of at least one opinion. At the end of the following link there is a table of costs to deliver various size rovers and some other comments relevant to your question.

http://wiki.xprize.frednet.org/index.php/System_Overview