I'll add the bet-mar is ok for supplies. His expertise seems to be better for wine and he pushes his kits. He has a good selection of grains in the back in bulk so if you don't see it packaged then ask.
The Hopyard is the head brewer for the Old Mill Brewpub. Good advice when you need to get an opinion on something you're brewing.
The water is soft so adjustments are for the most part additions. No need to dilute to lower a concentration of an ion. Most brewers I've talked to don't bother too much with water chems.
There's also the brew club. Palmetto State Brewers at palmettostatebrewers.com. The website is dated and the forum has sort of moved to Facebook but the club is active and hosts a competition, does beerventures once a year and a couple of parties. Also does regular brew sessions at a members house. A couple of members are in the Chapin area.