The buyer's obligation to pay the price includes taking such steps and complying with such formalities as may be required under the contract or any laws and regulations to enable payment to be made. Where a contract has been validly concluded but does not expressly or implicitly fix or make provision for determining the price, the parties are considered, in the absence of any indication to the contrary, to have impliedly made reference to the price generally charged at the time of the conclusion of the contract for such goods sold under comparable circumstances in the trade concerned.
If the buyer is not bound to pay the price at any other particular place, he must pay it to the seller:
at the seller's place of business, or if the payment is to be made against the handing over of the goods or of documents, at the place where handing over takes place.
If the buyer is not bound to pay the price at any other specific time, he must pay it when the seller places either the goods or documents controlling their disposition at the buyer's disposal in accordance with the contract and this Convention. The seller may make such payment a condition for handing over the goods or documents.
If the contract involves carriage of the goods, the Seller may dispatch the goods on terms whereby the goods, or documents controlling their disposition, will not be handed over to the buyer except against payment of the price.
The buyer is not bound to pay the price until he has had an opportunity to examine the goods, unless the procedures for delivery or payment agreed upon by the parties are m-consistent with his having such an opportunity.
(From: United Nations Convention on Contracts for the International Sale of Goods. Document A/CONF.97/18, Annex 1. Articles 54,55,57,58)