Holy Fugg. It's not that difficult. Whatever you buy, if you price it reasonable it will sell and sell pretty quickly.
I started in business before most on this forum were born or a twinkle in their daddy's eyes. I was in business in 1955. I was a securities broker, owned three real estate companies, one guide outfitter company, and for entertainment I buy and sell heavy equipment. So don't need any lessons in how to market a product. Rule #1 is knowing your "market". Rule #2 is don't overpay. Rule #3 is having a plan. Rule #4 is don't pay any attention to those who think you're a fool, and that they know your business better then you.