I don't think a lot of people realize how much body language translates for snakes. People who get bit and act freakishly cautious around them most likely make the situation worse.
It's worth noting that snakes bite as a last resort. Your snake is more than aware of how little a bite hurts you, and the danger that it entails (losing teeth, angring whatever it bit, etc.). Getting a snake not to bite is as much keeping it as comfortable as possible as it is convincing the snake that biting is a useless endeavour. If you come at the snake sheepisly, slowly moving in to grab it, pulling your hand back if you go near it's head, etc., you're doing what a predator would do. I sincerely think that if one acts with more... intention when it holds a snake, as in picking it up as if it were something accepted and everyday, holding it naturally/casually, but still keeping it comfortable and supported, etc., the snake somehow "knows" that it's ok.
I don't breed my snakes, nor do I display them. They sit out of sight, in a walk-in closet, and I keep them soley to entertain me. Thus, the only reason I keep snakes is to handle them, to be fascinated by them. I have been known to sell aggressive snakes (A hondo milk comes to mind. Of course I told the buyer, my friend who wanted her because she was a good-looking female to breed.). Still, I would not sell a snake because of one bite, or even 5. Snakes aren't exactly smart, expecting them to tame like a dog is just beyond their capacity. They will get used to handling, but they hardly *enjoy* it. Snakes just bite, and the reason doesn't have to be something that we think of as significant. Maybe it was a little warm at the time, the wrong time of day, or not feeling well, or stressed from people around. Hell, it could very well be something as insignificant and absurd as... oh, the snake was on it's way to take a dump, or maybe you just caught it at a bad time.
Regardless, a single bite isn't reason to sell the snake, or even change how you're doing things. Unless biting happens frequently or at least a couple times, chances are you're doing nothing wrong at all. Keep him, handle it every few days, early evening once it's been dark for a while. Use a hook or something hook-like (I use an old metal shishkabob skewer that I bent into one) to pick it up, and set it into your hand. Don't pet it, go near it's head, constrict its motion, etc., and I'll be willing to wager that he'll be fine. Eventually you'll be more bold, and you'll slowly figure out exactly what the snake will tolerate. It's not something you have to pay a lot of attention to; you just naturally learn. I've only had Isabel for a few weeks, and I know that if I hold her within two days of eating she's cranky, that if I hold her before 5 or 6 PM she'll probably bite, and that she's more calm if I wash my hands with unscented soap first (as opposed to this weird spring fresh stuff in the kitchen). OTOH, Taj, my Mex. black king, doesn't seem to care about the soap, hates sunlight, acts very aggressive but never bites (he always looks like he's ready to, but literally NEVER does)... and he'll musk if I don't pick him up initially with my skewer/hook.
Bottom line, you can sell it if you're truly uncomfortable, but your snake is not aggressive because it bit once.