Probably depends on options as well. A stock bike won't sell for $20k, but one with a ton of upgrades might.
I've been hanging onto my stock stuff. I put a post on here before asking if it was worth it to keep or sell and a lot of people said that you can get just as good a price for stock and then sell the aftermarket stuff separately. Personally I'd rather sell it and get rid of it since it just takes up space in my garage. Also, now that I've done the bars, it would be a pain to put back to stock. Everything else is quick bolt on parts though.
Here's my rule on selling stock parts, leaving aftermarket stuff on the bike for sale trade.
Whatever I can put back to stock in a day's worth of work before selling/trading the bike, I'll do. If it takes me longer than that, it's not worth my time and I just consider that a "pay it forward" to the next owner.