This mod will allow you to sell rocks, metals, sketches, relics, gems and even insects by replacing the “Buy” interaction on the Consignment Register.
You can sell pets if you have any (even though I would not recommend doing that in real life). Once you have installed any pets, you will be able to see an interaction saying “Sell Pet” that will be added not only to consignments and pet stores in your town but to social interactions between friends so that you can profit off of your pets. Voyeurism and spying may be a massive no-no in real life (without consent). However, in Sims 3 they are both allowed and advisable since they can definitely spice up your gaming experience. You’ll be able to spy on any sim of your choice and be able to identify them when they are nowhere to be seen by you (“you” reference anyone?).