A lot of comments very dismissive of anything "print on demand". As an author of a niche book in both hard/soft, I chose Lightning Source/Ingram because they produce quality books. At that time (2012) I could have gone the "easy" route and used Amazon but even then there were complaints about quality. I've received quite a few compliments about the physical quality of my book, primarily the paper back edition which I believe was 60lb cream paper stock.

Note that authors who take the easy way and use Amazon KDP w/ extended distribution appear on sites like BN, Books A Million, etc via the Ingram distribution but the physical copy will still be printed by Amazon and be inferior.

Some clues you can look for in general are - Amazon in the past two years has basically stopped stocking non-KDP POD books so they will almost always say avaialbe in X weeks (or if "Prime" 3-5 days). Amazon books are almost always a page count divisible by four and IIRC 828 pages is a limit on many trims.

So if you buy off of Amazon, check first to see that the Amazon listing looks like too.

It is really unfortunate that Amazon (and a few places in India) ruin it for everyone.