Sip2dial is one of the leading cloud contact center software providers across the globe. We help contact centers of every size create powerful customer connections. Our call center software creates more successful customer interactions by increasing the productivity of your contact center.
Take a look at Apptivo, their invoicing app is suitable for small business. If you're looking for something pretty affordable choice with unlimited invoices. I think it can fulfill your financial requirements.
Check this out: http://www.apptivo.com/apptivo-mobile-invoices-app/