I have been amazed when I’ve given a talk on downsizing, when some people come up to me afterward and tell me that they have downsized already but still have all of the stuff from their former home in storage. This is because they would rather pay the storage fees than suspect that they got any less than top dollar for the items they have stored.
That is why I like to recommend this book by Harry L. Rinker, “Sell, Keep, or Toss? How to Downsize a Home, Settle an Estate, and Appraise Personal Property”. In the book he takes you through the whole process of getting rid of your stuff. He starts out by telling how online auctions have changed the value of items that were once thought scarce and instead are showing up in the thousands on auction sites. He informs you that the price for items you see in antique and collectible guidebooks reflect the price you would expect to pay in a retail store, not what the dealer or collector is going to offer you. After getting you to accept realistic prices for your stuff, he spends the rest of the book showing you all the ways of disposing of your items. He breaks down the downsizing process into step by step plans.
You would feel more confident following his instructions than you would getting advice from the cousin of a friend of a friend who knows someone.