1. You can build nuc boxes pretty cheaply per the instructions in the video at the bottom. Using one board makes a nuc box, and IIRC, the board costs about $10. I like this size because I can put an inboard feeder in with sugar water, along with five frames. If you want to sell, the thing that takes the longest is getting the comb built and the queen laying and hatching.
2. When you sell, buy the corrugated boxes that have the wax coating (think of fruit boxes with that waxy coating). They come with a circle in the front that you can buy plastic stops to close when you sell. I put the bees in the box during the day, then close them up at night for sale that night, or the next morning (move the box as soon as you close it or you can get bees congregating which is a pain. I just wrap duct tape twice around it to hold it closed for transporting.
3. It is a good way to get rid of some old comb. Once your queen is laying, you can take resources from your other colonies to fill up the nuc. Two honey and pollen plus 3 brood frames should do it. It is a great way to rotate some of your old wax out and replace it with new foundation in your established colonies.
4. Remember, you can make bees, or you can make honey. The more you split, the less (or none) honey your bees will make.
I just list it on the bee club website for sale, or craig's list (more on craig's list)