If a book has an isbn, I google it at Amazon first. That gives me an idea if it’s worth listing. I don’t compare to Goodwill or Half Price Books or any of those ‘charities’ because they have an unfair advantage and you simply can’t compete. Scroll down to sellers by real people and line up with that. If it’s a first edition, so stated or full number line, usually, that’s considered collectible, as is a signature by the author. No isbn, or for a bigger scope of info, simply google it.
Amazon will take 4.89 on a 9.99 book. Yes, that much. eBay takes 20 per cent and pays you quickly. I figured that a bit adds up, and is better than just donating them. Amazon, you list it once and it stays on. No charges if you have any number of listings. eBay gives you 250 listings. 39.99 for additional 250, per month.
It is a learning curve thing. I sold my first few books way too cheap, including some really good ones. I add to my collection of books at yard sales, library books sales, and word of mouth. I have picked up books for a dime and sold them for over $200. What sells for me are hymnals, how to, prepper books, and school books.
Still ‘growing’ this as a business, but have earned about $5,000 this year. Good money if other venues aren’t there.
Postage. Amazon provides 3.99 per book, regardless of size, and it does average out. eBay, customer can pay or you can raise your price to offer ‘free’ shipping. I find people would rather pay more and get free shipping. Cardboard for protection and brown paper bags make economical shipping materials.
There are different editions, different printings sometimes of the same book. It’s best to match. If that doesn’t work, you can list it as similar, and include a picture. When in doubt, price high. You may get it, or you may get an offer that you can decide on. Some business ask insane prices, like $900 for a nothing book. Apparently it works for them.