great customer service should always come at a premium
A nice customer service story which demonstrates a great point to small ISV's out there. You should pretty much always charge a premium for great customer service. In fact, it's worth letting customers go away and come back as long as you can really live up to your end. I've already made dozens of decent size sales where people tried HelpSpot, then tried another help desk tool and finally came back to HelpSpot because they couldn't get their questions answered, get timely support and so on.
This is a really important consideration when working out your maintenance pricing. If you're providing top notch customer support make sure you're charging for it. Don't be tempted to simply match the competition or under cut them. People like to pay for the best as long as you really are.