Choosing the RM-E (Rights Managed - Exclusive) licence on Alamy will allow for one time use as far as i know. At the very least it can only be sold to one customer - not sure of the customer can use it more than one time though...
http://www.alamy.com/contributor/help/image-licences.asp
http://www.alamy.com/contributor/help/image-licences.asp

none have sold yet. Hang on let me check again... nope, still no sales. 


Not one single view and I have about 65 images up with them. 
