I love blessed sacramentals. They greatly enhance prayer, but you can never sell them, or they lose the blessing. That is because it would be the sin of simony to attempt to buy spiritual things.
We can buy rosaries and miraculous medals of course, but we must have them blessed after we buy them, and we cannot buy someone else’s blessed item and expect to retain the blessing.
I bought blessed water, oil and salt from the internet once for a steep price because they were advertised as blessed by the Pope.
My priest said, oh boy you got ripped off. Even if these sacramentals were blessed in the Vatican, they lost their blessing as soon as I bought them. I contacted the company and told them, and they offered to classify my money as a donation or refund it. I said no thanks, I cannot accept it because I am the one guilty of attempted simony. I asked them to please stop offering blessed items for sale, as that is false advertising. Sold items cannot retain their blessing