You won't need six regulators, unless you plan on having different levels of carbonation for each keg. I have been quite happy with one reg on 6 kegs for some time. Two would be nice for different styles, or to force carb a beer while serving another. As for the best place to buy from, well, everyone seems to have their favorite. I personally value good customer service over rock bottom price, especially since the prices aren't all that different. Try Keg Connection, or your favorite online HB Supplier.