Legally (or morally), isn't there something wrong in keeping the ripped tracks while you are selling the original discs?
I used to think so, and the subject still confuses me somewhat, but have currently settled on this thought:
1. If you want the tracks ripped, why keep the trinket-CDs around.
2. If you aren't to sell them, then you must give them away - which is still "immoral", as the recepient is also depriving the labels of money by not paying for them.
Presumably if the seller does make money, then they might continue to buy music with this money as they have done before - in the original poster's case, perhaps as digital downloads which have a greater profit margin.