Throughout human history, for as long as we have venerated people, places, or things as holy, there have been people who have wanted to blur the lines between faith and commerce. Sometimes this tendency is innocent enough, at other times it’s cynical and exploitative.
The Church makes it very clear that the sacraments are not for sale. Sure, your local parish may request an offering to host your wedding, but that’s to cover the costs of the staff involved and the expense of maintaining a big building. If you can’t afford such an offering the pastor can waive it. Just don’t turn around and spend $3000 on flowers.
The Church also discourages commerce in sacred objects. Once an object has been blessed—a rosary, for instance—it should never be sold. It’s different if you’ve had your car blessed; most people wouldn’t consider an automobile a sacred object. But the epitome of a sacred object is a relic—usually a piece of bone from a saint—and the church law explicitly prohibits the sale of relics. This is to prevent abuses and fraud, and also because it profanes something sacred, part of a person’s body, and turns it into what today might be called a “collectible.”
If you look on certain internet auction sites today, you’d see lots of relics, liturgical vessels, and other sacred objects being offered for sale. In some cases, the item description says that only the case of the relic is for sale, and that the relic itself is a gift to the buyer. These ethical gymnastics may appear to side-step canon law, but they don’t resolve the ethical and moral implications of buying and selling something sacred, especially a relic of a saint’s body. If you see these items listed on an auction site, please don’t bid on them, and report them to auction site’s administration. They may not care about Canon 1190 prohibiting the sale of relics, but their own terms of service prohibit the sale of human remains or body parts.