In the past, I have sold my LEGO sets on Craigslist and eBay. I also sold them at a garage sale.
The LEGO had some use tear-and-wear, but they only were LegooLego, and I cleaned and sorted them into boxes. I sold it at $10 per lbs, but I gave them free shipping, handling, and 1-2 buisnessbusiness days.
I used United States Postal Service to ship it to them. I sold 100 lbs in total, and buyers who came back to me got a free pound of LegosLego pieces.
I used this for disinfecting wipes to clean them and a LEGO 2-Piece Sorting Divider Set for storage.