Is it permissible for a Muslim to buy perfumes at wholesale price and then sell them to relatives at a higher price to make a profit?

If the buyers know that you will buy and then sell to them, making a profit from them, there is no objection to that. However, do not sell anything to them until you have first bought it and taken possession of it, based on the saying of the Prophet, peace and blessings be upon him: "Do not sell what you do not possess."

Therefore, you are not permitted to conclude a sale with them until you have first purchased the item and taken possession of it.

However, if you are merely an agent for them in the purchase, you are not allowed to add anything to the price of the item. Rather, everything you receive in terms of gifts or discounts belongs to them, because an agent is entrusted.

If you wish to profit from them, inform them that you are a seller, not their agent, and specify the selling price for the perfume they desire. If they agree, you can then buy it and sell it to them, and you are not obligated to inform them of the price at which you purchased it.