WHMCS is the way to go
Clientexec is also a good billing/support control panel and it does not cost that much; very affordable.
He is probably asking for a software that will auto create, bill, and manage. Basicly what whmcs does. But, I dont know if hes willing to pay or if he wants it free.
If your willing to pay, I think whmcs would be good. I dont know any free ones, sorry.