Before buying a bunch of products, why not start with the basics? Have you been at a dermatologist or a specialist to understand why there is a bald patch?
What you tried on your own?
Check out this thread http://www.longhaircareforum.com/showthread.php?t=168415, post #14...she used this to grow in a bald patch.
I was going to suggest the same thing dachsies_rule said. That recipe Nonie posted works