Try Studio Cloud. It has a free desktop version, and the upgrades allow you to do some pretty cool stuff. It is fantastic for tracking clients! I don't use it for invoicing, etc. but you can use it for that as well. (I already had Quickbooks set up, and wasn't going to switch everything over since I was already "committed" to it.) But the referral tracking and "relationship" tracking is pretty cool!
Try it out before you drop a lot of money on something else. And if you need any help setting it up, don't hesitate to ask!