I need a booking management software for my business

I need a software that I can use for
- booking jobs,
- send quotes and invoices
- be integrated with Xero
- schedule appointments,
- assign jobs to my engineers, so they can receive them on their phones/tablets
- engineers should be able to edit, attach photos to each job
- each job should have a start and finish buttons, to measure how long the job took.
This is what I need in a nutshell,
Do you think you can give me rough estimate on how much would this project cost?
Also I dont want this to be a subscription type software. I want to own this software outright.
Many thanks
Vinnie