Parametrizing form and transform XML response to JSON

I have a working website that fetches air flight information, but right now the user needs to press a search button to fetch the flights available in a given date and after that the user needs to select one of those flight to be able to view the price of that flight. This is not efficient as I would like to get the prices from all the flights and routes before selecting them. I need a freelancer who could do this, as all the behaviour is done, the only thing he or she would need to do is 1) Parametrize (GET or POST) the different fields as it was an endpoint 2) display the results in a way that is easily fetchable, displaying the information in JSON. I can provide screenshots of the actual system if needed. To be sure that you have already read everything here, please start your proposal with << I know my stuff >> or they will get ignored. The technologies for the system right now are PHP for the main files and Javascript for making the asynchronous calls that get the information of the flights. So, summing up - basically I need to combine all the information that a user can get when searching flights using the system and then for each flight call the price getter and display it as a json object. I will provide screenshots and more information upon request.