Hi.
I understand that you need betting software on php, but for that you need webserver to run that software.
Anyways, timeline will be differ based upon what you need.
I need more details to confirm how long it will take and how much it will take.
If it's as simple as Lay and back you mentioned, really easy and can be done 50$ one day,
but usually betting software is not that easy like that.
so if you give me some link as reference, that would be nice.
Regards