'Buy' in the Bible

I advise you to buy from Me gold refined by fire so that you may become rich, and white garments so that you may clothe yourself, and that the shame of your nakedness will not be revealed; and eye salve to anoint your eyes so that you may see.

and he provides that no one will be able to buy or to sell, except the one who has the mark, either the name of the beast or the number of his name.