Buddhism as a form of trade

Mongkon Bohpit Buddha image were sculpted by bricks and countless tiny Buddha images that were given away by Ayuthya people as their contribution and cast by plaster. It was made during the beginning of Ayuthaya period.
In this present time, small stalls sandwiches the walk way from car park to Vihara Mongkhon Bophit. Their products were targeted towards pilgrims and tourists.
In Buddhism practices, exchanges are made all the time. As an equivalent comparison of buddhism to capitalism realm, temples and its complex can be viewed as a form of economic trade. Visitors expect an 'object' or a 'product' from the place and are willing to give some sort of 'currency' or 'mediator' in return. In Economy, the currency often is money.
What is the currency in Buddhism practices then?