There is an expensive medical bed, over 500 sci-fi books that when put into author lots - sell well. A bunch of easy to sell chairs in a garage sale. Lots of things that will do well in a garage sale or FB, not so much that will do well on eBay though.

You can tell all the people running the Estate Sale that you will come with guys and a truck or trailer the Tuesday after the sale and take everything out free of charge. you want to make it worth their while. A lot of them have to pay a company to come in afterwards and do a clean out. So if you can do it for a couple hours of labor cost only and get a whole bunch of free things. You now have free inventory. Even if it’s not that great of stuff, you can still put it in your garage sale for a dollar an item.