Why?

Why every semester will face problems with getting the textbooks?

First semester,got our textbook late but it was a good book.Second semester,got it very late and the book was not that good.Tried to get the other publisher but ALL the bookstores did not have it.Finally,after searching for so,so long (a month before exam) managed to get it from ebay.

Now,the third semester..Know that the college will be providing the 'not-that-good' book and will be late,so thought of taking a step earlier and get the book before lectures start.BUT..can't seem to find the book.Friend wanted to get from MPH but there is none.I tried finding on ebay but there is none.Tried the official website for that publisher but there is none.

Where else should i find?