Need a Paypal API/ PHP expert to fix a bug on wordpress site

Hello, I used Event Manger Pro plugin in my website for the Event booking. There have option to buy tickets for each event. But i added custom code to do extra charge for few items there on every tickets and it works nicely with Paypal. I am just getting error when the value is 0 on extra pricing option. I think that is very silly mistake on my code or if you can use a better logicial statement into my code it would be best. Here is the example of my code in pastebin. [login to view URL] In that code [login to view URL] its working fine but if someone select 0 as quantity then code not working under that statement. another code i applied, [login to view URL] Please have a look that code and share you thoughts. I need it done urgently may be in few hours today. If you have any question, you may feel free ask. Dont send me spam/ random cover letter. Be specific on that job post!