@outlander, the ones you don’t like, choose a couple of new colours, and work the same canvases, new colours over and into the old, like layering, and see if you are happier with them.

If you don’t like them as they are, you have nothing to lose except the cost of the extra paint ..... but if you’re selling them off anyway, you will recoup those costs.

Choose your pricing between the cheaper ones you can find in discount stores, and professional ones at high-end art stores and see how you go.