FM Solution for freelance hours/expenses?

Hi all,

I am self employed, about 1/3 Filemaker, 2/3 web design for about 6 clients. 

Currently I keep track of my hours in TimeTag - which simply records time worked and category. And I manually process my invoices and expenses.

I have been investigating a more comprehensive solution for this, not that my current system is overly cumbersome, I only spend an hour or two a fortnight on invoicing. I was looking at all the different solutions out there, but none of them are exactly what I want.

Then I realised, I have a hosting account, a FM licence, why not just build exactly what I want? Project tracking, hours, expenses, invoices etc The pay off may take a while time wise, but it would be handy to click a button to produce my invoices fortnightly and reports for tax time.

Has anyone else out there built their own solution for this that they might like to share, or know of a starter solution for this?

Thanks heaps and would love to hear your views