FMV Depreciation Based on Amazon Resale Pricing?

I now agree with the justification for deducting a portion of ETV value consumed in the reviewing process. The question then follows about how do we calculate and apply the amount in our books?

I've read some methods such as by u/callmegorn who uses a percentage table based on whether its a brand name or generic. u/Privat3Ice says she uses thrift store values. Several people mentioning Goodwill's valuation guidelines. u/pankcakeman2018 is using a flat 70% off (if I understand his method correctly.)

Today, I remembered Amazon Resale (formerly Amazon Warehouse.) Do you think that might hold more credibility with the IRS? In some ways, Amazon Resale offers more customer service than we get...

https://www.amazon.com/Amazon-Resale/b

What is Amazon Resale?

Amazon Resale (previously known as Amazon Warehouse) offers great deals on quality used, pre-owned, or open box products. With all the benefits of Amazon fulfilment, customer service, and returns rights, we provide discounts on used items for customer favorites: such as smartphones, laptops, tablets, home & kitchen appliances, and thousands more. For each used product we sell, we thoroughly test the condition of the item and provide detailed descriptions to make it easier for you to make a decision.

We don't have any returns rights, although we do have the ability to account for damage losses on a Schedule C. But we ARE thoroughly testing and it's documented in our reviews.

Amazon does not publicly share something as easy as a pricing valuation table, but they DO share their product condition tiers, which we could easily adapt to spreadsheet tracking.

How can I understand a product's condition?How can I understand a product's condition? 

Since each item is unique, we use detailed descriptions to help you better understand the item condition, by describing its appearance, functional qualities, accessories and packaging condition. We provide all the detailed information on the product condition right on the product detail page, to help you make your decision. Depending on the item condition, you will find that some items have even deeper discounts.

Used - Like New: An item in perfect working condition, the packaging may bear some damage. The item fully functions, and all its essential accessories are complete.

Used - Very Good: An item in very good condition that may have seen limited use and fully functions. The item may have minor cosmetic imperfections. It may arrive with damaged packaging or be repackaged and could be missing some non-essential accessories. Missing accessories are shown under individual item description.

Used - Good: An item in good condition that may show wear from moderate use and fully functions. The item may arrive with damaged packaging or be repackaged. It may have minor cosmetic damage, such as a small scratch. The item may be missing some valuable accessories and it may not be used until those accessories are purchased separately. Missing accessories are shown under individual item description.

Used - Acceptable: An item may have clear signs of usage but still serves its main function. Item may arrive with damaged packaging or be repackaged. The item may have cosmetic damages on it or show other signs of previous use. Signs of usage can include scratches, dents, and worn corners or edges. The item may be missing some valuable accessories, components or spare parts, and it may not be used until those parts are purchased separately. Missing parts are shown under individual item description.

Used - As Is: The item may have extensive wear or cosmetic imperfections but still serves its main function. The item may arrive with damaged packaging or be repackaged. Images will be provided to show the exact condition, including any package damage. The item may be missing some valuable accessories, components, or spare parts, and it may not be usable until those parts are purchased separately.

I'm not suggesting that it's a good idea to price match our items, many of which are not going to be available on Amazon Resale. Nobody has time for that. But maybe taking a look at their conditions ratings and getting an idea of the discounted amount (that I read goes up to 70% off) could be useful? Seems very reasonable if one had to defend the depreciated value of Amazon items to the IRS.

Obviously, Amazon has a different motivation than we do. They have more overhead involved in handling the returned item (incoming returns and the resale expenses) so they want to get as much money as possible.

I checked just one item and found an Amazon Basics drill in "Like New" condition selling for 7% less than brand new. But that tells me right there that 7% could be the minimum starting point for lost value on open box items. Then again, perhaps the more aggressive strategy about thrift pricing is equally justifiable.

Haven't read anyone else mention this, so thanks for putting up with another tax thread in the main group. For those of you who are running vine through schedule C, what do you think?