The average LEGIT producer I see sells beats around $20-25 and they sell their exclusives from $200-$1000+. Personally, I sell my leases for a penny under $20 & sell my exclusives for no less than $500.
Part of the reason why I never sold leases for $25 is because I never saw myself up to par with some of the top producers who sold it for that price and another reason is because I could say, well, "this producer sells beats for $25, I sell mine for $19.99! you're getting a deal here," so honestly, sell what you think you're worth and make it reasonable but not too outrageous to the point that someone cannot afford it.
Also, if you're gonna sell expensive beats, make sure that you are all about quality. Your website, graphics, online appearance and way you conduct yourself has to be ALL about quality. People HAVE TO know you are the business at the first glance (Think Apple!) & the majority of the time, having such a "quality" appearance is not free or cheap.
One thing I realized too is (heading back to the point,) sell what you think you're worth, because people will buy if they like your music and think they can do something with it. Believe me.
By the way, exclusive sales usually take longer to sell than a lease and Fataltone asked some pretty legit questions that you should really try to answer if you want to do internet selling.