When selling your beats online or offline you can go about selling them two different ways. You can sell them exclusively or you can just simply lease them.
When you sell your beat exclusively to an artist, you are giving that person full rights and ownership too that whole beat. You can never reuse that beat again or resale it without the permission of the artist you sold it to.
When selling your beats exclusive you can sell them for a lot higher price than you can leasing rights because you are giving out full ownership. (I WISH SOMEBODY WOULD HAVE EXPLAINED THIS TO ME WHEN I FIRST STARTED OUT!!. . I was selling my beats exclusively for just $20!! big mistake :-( But basically you can charge a lot higher because you are giving away full rights. Your price you charge for exclusive rights depends on you and what you feel your beats are worth. I now charge no less than $500 for my exclusives.
Leasing rights are basically selling limited rights of your beat to an artist. They can use the beat and record their song for a demo, mixtape, myspace, etc, but you still have ownership to the beat, which means you can continue to resell as many times as you please and continue to make profit of the same beat unlike exclusive rights. In the long run if your patient leasing rights pays off which is way I know longer try to sell exclusive rights.
Basically the decision is up to you. I used to want to be quick to sell my beats exclusively because I was getting a lot of money at once but now I see that leasing my beats is better because yes I am getting less money but I am still keeping ownership of my beats and I can continue to resell it over and over again as many times as I please.