I would say it all depends what type of artists you are selling to if they are local or "Industry" by that I mean already have a record deal
usually when you lease a beat you still maintain full ownership of the instrumental itself and you the artist using the track is usually limited to what they can do with the song, Like they maybe able to use it for profitable use for only up to 1 year or only aloud to sell up to 1000 copies of the song. I seen da prices range on these leases from $10-$100 depending on how good the actual song is. although they are a lot cheaper than exclusive rights a lot of producers make more money off this since more people have a lower budget when it comes to their music because they have to consider paying DJ's to spin records at the Club,Radio,Events,Etc.... and the actual cost of putting a Mixtape or Album out.
Exclusive Rights are for more serious artists or people who have a bigger budget to work with. When selling to these artists it's usually unlimited to what they can do with the track (Demo,Radio Play,Album,Mixtape,Ringtones,Digital Download Etc...) You can chose to keep your copyright so that you get album credits and points these on the prices
go from anywhere of $100-$3000 usually when your a small time producer if you were Timberland or Kayne West your talkin $20,000 and up and thats their cheap beats
thats pretty much the basics of the whole price thing I can suggest you get a Soundclick account and pretty much the artists come to you and start buying away.... another Suggestion is Voice Tagging your beats this means to talk over the instrumental so no one steal your beats
I actually have an R&B/Pop singer I work with and interested in hearing some of your work send me over a sample...
knaledge609@yahoo.com look foward to hearing some great things
I wrote a lot but hope it helped in anyway