First of all thanks a lot for a very powerful and easy to use software( Backendless Pro) and I love it. there are a lot of
developers who is looking for an easy to use yet powerful backend. In my idea it is even far more powerful than Firebase.
if you sell it like regular software products such as photoshop etc. for a fixed price whatever you think is best for your business; by considering a huge amount of individual developers who are not able to pay existing prices but are able to pay a fixed price suppose less than 1000$ I think the product will find a lot of buyers like me.