Dear Noorulbs,
Greetings!
As we have 15+ years of working experience doing core PHP/MySQL - we are confident doing similar API task.
Here, It is difficult to give you close estimation as we do not have much information in your post. Ideally, we will need code access and list of features to add, we can better get your ball park cost.
Anyway, we offer USD8/hr of working and hourly basis/weekly paying offer.
Let's discuss further.
- Prakash
WeTheDevelopers