Square Payment Option For Event Registration Form

I have an online event registration form that provides registrants with the option of paying by cheque or PayPal once they have submitted their registration.
The User's name, email address and amount to be paid are passed to Paypal to prepopulate the PayPal fields.
The existing form and connection to PayPal is written in PHP.
The connection to PayPal is using a Buy Now button.

I would like to replace Paypal with Square Payments as the online payment method.

The connection to Square could be a Buy Now button or an integrated Square payment form in the Thank You page registrants see after form submission.

I will provide FTP access and Square keys and tokens.

Please, ONLY respond to this project if you have experience integrating a PHP form with Square Payment Systems.

Please provide your fee and time to time to complete.

Thank you.