Listing a property after making a cash offer

[Carl Schmitt]

When people run a direct mail campaign, It sounds like there are always a few that want to sell but only at retail pricing. If your first attempt is to purchase or wholesale the property, you make a cash offer and it isn't accepted, is it then legal (or ethical) to list it if you're also an agent? I'm not in this situation, but I've always thought it would make sense for a wholesaler to also be licensed. Then, if they can't assign the contract, they could just list it. Is this legal?