Cordless tool batteries

I have some cordless B&D tools and am please with them. However, I need to buy some more batteries. I'll be taking a step up to the "gold" batteries (I think it's "gold"). I can do my own internet search but I wonder it anyone has found a good supplier for other replacement batteries (i.e., not B&D, Lowe's have these). I have a DeWalt 9v cordless drill, a Makita 14v cordless drill and a Makita 14v cordless circular saw. I have only found 3rd party batteries and my concern is whether these batteries are really any good and if the suppliers provide good followup service, when needed. Anyone got anything on this? Tom