DO: Expense your Costs of Good Sold (COGS) COGS can be confusing, but it shouldn't. Use this simple rule if you purchased items to re-sale on eBay: COGS is the actual price of the item that you are selling at the time that you paid for it. The IRS does not care about 'current value', they care about actual cost.
If the item you are selling is a personal item that you have used and now wish to sale, get a current estimated value of an exactly duplicate or very similar item that is selling today. Where can you get that value? eBay of course! There are some great tools to help you get this information. You might want to check out Terapeak (www.terapeak.com), HammerTap (www.hammertap.com), or Vendio (www.vendio.com).
Some collectables like comics, antique toys and such may increase in sale price significantly resulting in increased profits.
Meanwhile, some aging electronics lose value each month which may result in a loss or write-off for your business, offsetting other profits.
The bottom line? Whatever you do, don't miss this tax deduction!