I am currently using Zoho for my company CRM, the only challange is the mobile web interface is a little wonky.
I have been evaluating the latest from MaxamizerCRM 10, it is an upfront cost but it works out way cheaper in the long run.. plus it has an outstanding Blackberry application. You can send email from the application etc.
As for the payment side of things, we have used several different online/offline applications. When we were smaller we used Freshbooks.. pretty cool for invoicing etc.. but you have to use a payment auth company on the back-end....now we use PaySimple.. all the invoices are sent to the customer from CRM with a "PayNow" link. that shoots back to PaySimple, customer pays.. we get an email saying they paid.. aint it great.