The pricing is always changing when you refresh the site or log in/log out.
The reason is simple: when you refresh the site, the system randomly mixes another group of curators according to the selected genres.
This allows other curators and playlists to receive the song, so they have the same opportunities.
This explains the prices' changes because different curators' groups will mean other playlists with a different impact.
For example, if in the category Folk, there are 100 curators available and you are targeting that music genre, let's say that the system initially shows you 20 of those 100 curators for a price of 100 USD. Then, you refresh the page, and you will get a price of 110 USD, but this time for 15 of those 100 curators.
Why the price changes even though now you see fewer curators?
Because the new curators generate more remarkable interactions.
Following the example, in the second situation, even if the group of curators is smaller, it is safe to say that according to our records and algorithm, that group has a higher price because they tend to provide high influence for the artists, helping them to be listened or discovered, or having more engagement on their playlists.
That's, basically, the way it works.