Welcome! Good to have another paperphile with us.

Since you already work with heightfields, I suggest you try out Wilbur:

http://www.ridgecrest.ca.us/~jslayton/software.html

It's written by Joe Slayton, the same fellow who wrote Fractal Terrains for ProFantasy, and he's also a member of these forums (Waldronate), so hunt around for his tutorials. "Fun with Wilbur," I think is the title of them.

You might look at the map galleries on ProFantasy's web site before you put down any money. CC3, while powerful, is best at making a certain kind of symbol-driven map. Although its capabilities are growing, if you prefer to work with shaded relief or more photographic type maps it's not the best tool you could choose. I don't mean to downplay PF products, though. I use them, myself.

I'd hunt around these forums, see what kinds of maps you like the best, and let that guide you on what software you choose. Of course, items like Gimp and Inkscape are free, so you really can't go wrong there, and that savings will let you put your money toward buying a drawing tablet, which I highly recommend.

Anyway, good to have you here, and have fun!