It's always eye-opening for me to read about people's experiences with bad dive shops here. My LDS has
1) given me unasked-for discounts on just about everything I've bought from them, when I was already handing over my credit card,
2) given me small things like regulator port plugs, an occasional fill, and a T-shirt for free,
3) educated me on products they don't carry but that might better suit my needs,
4) talked me out of buying things from them that wouldn't suit my needs,
5) offered to let me return stuff I bought from them even after I'd used it if it wasn't meeting my needs,
6) let me try stuff out for free to see if it would work for me,
7) remembered my name, introduced me to other customers as potential dive buddies, asked follow-up questions about the dive I had told them I was going on the last time I was there, and generally made the shop feel like my own version of Cheers.
Granted, I've spent several thousand dollars there, but they've earned every cent.