It's not rocket science learning to make your own rap beats that you can sell because the truth is all you have to be is enough of a rap fan to know what kind of beats will sell. There is a major difference between beats you may personally like for yourself and the type of beats that people are going to want to buy from you. If you know the difference between a good rap beat and a hot rap beat that gets played on the radio and in the clubs you understand that the beats that you make that are geared towards the radio and the clubs are going to be the beats that sell faster. That is not at all to say that underground beats won't sell because they probably will. It just means that you must cater your beats to the type of artist you want to sell them to and most of the rappers today want to make money off the music that they make and the rappers that are making the most money get played in the clubs and on the radio.
A hot rap beat has a few parts you should typically understand and I will show you a very inexpensive program that comes with the same sounds that you are hearing used by big time producers. The drums are crisp and they are already pre mixed to hit hard. They are usually offset by a long bass drum sound pounding behind them. The high hats typically roll every four to eight bars. There are most likely about three separate background melodies that are each using different instruments or sound effects.
Start off just by listening to your favorite song or track with a pen and a paper writing down exactly how many different sounds and separate melodies you hear throughout the beat. Think about which ones are just effects sprinkled around in the beat and which ones are actually playing a definite rhythm. Typically, if there is something just sprinkled around in a beat it is normally just an effect or several effects but the actual instrument sounds are normally playing a melody. Then you want to get a computer program like the ones used to create beats that you hear new rappers over like Drake and Soldier Boy, who create these huge songs that sell millions of records from simply off their personal computers. You can find a very low cost one that comes with the exact same sounds mixed properly that you would hear on the radio or in the clubs.