There are millions of books listed on ebay. A search for " Donna Hay " shows over 3200 listings with only 182 sold in the last 90 days. When selling into a saturated market you need to find unique or rare items that are not in competition with thousands of other sellers. 

That is all completely true. I have to say though that I could be tempted by some Donna Hay books but they would have to be the right ones, on the topics I wanted.

I think gr's price on those books is competitive (from what I can see, compared to other listings) but as you said, there are a lot of other listings out there to choose from.

But more than that, most recipes are free online. Not all, by any means. But it is amazing just how many sites are devoted purely to recipes and all without charge. And for those that charge, these days we are often downloading those recipes directly into our machines for guided cooking, so the market for books isn't what it used to be. It's still there though.

 A great way to do this is to do an advanced ebay search on sold books over $40. ( Use the " advanced'  icon next to search bar at top of most pages ) You will soon start to see a trend with specific subjects and types of books that have genuine value.

Brilliant advice. I'd certainly be following it if I intended to start listing books.

One of the real strengths of ebay (in my opinion anyway) is that if you're after something a bit more unusual, something that isn't a dime a dozen in op shops etc, you can often find it second hand on ebay. That was my experience some time ago anyway when I was after a book with an ancestor's diary in it, or part of (No privacy for writing). Not a rare book at all, but one it would be harder to come upon by chance.

Because I wanted a couple of copies, I was willing to pay a reasonable price.