Each takes about 2-12+ hours, depending on the difficulty. I kind of work slow, but it's because I want to ensure the customer gets the best effort I can possibly put into it. Animating them can take an additional 10-30 minutes, depending on the animation.
If these are indeed pre-made(homestuck) bases like Ophibell says then, as far as I know, you will not be allowed to sell these, unless you sell them as pixel dolls in which case you will need to give a full disclaimer and have permission from the bases' creator to use them. Selling something that is not 100% yours in an art shop is plagiarism and can get you banned from the site