I would suggest something along the lines of YourKit pricing which seems to be industry standard for the most part.
Also their personal license which isn't advertised heavily is $99/yr which allows for commercial use but must be paid for by the individual rather than a business entity. I like this license because I like to take my tools with me and doesn't make me beholden to purchasing/procurement departments of the companies I do work for.
However, I can promise that the pricing model will be perpetual license based, NOT a subscription that "only costs you one cup of coffee per day"..