Automatically offer returning customers substantial discounts.
I've been a customer for years, and each time I need a new server, I have to go through this process where I point out I'm a long time customer and that I previously received a discount. Just do it automatically.
If Limestone wasn't so good, there's no way I'd be jumping through that hoop. Some people might like haggling; I find it insulting that I get charged more by default if I don't ask for a discount.