Depends on how he presents his book. For example, Hank Hannegraaf states that his books are essential if you truly want to understand the bible and be a strong Christian. If his books are essential to obtain a full understanding of Christ (his claim, not mine), then it is immoral for him to profit on it. It's no different than selling indulgences, IMO.
Now, if Hank wants to have a basic book for cost, and a fancy book for a profit, that's fine; that's the way Bibles work. You CAN spend a lot for a Bible, you don't HAVE to.
It's the same with Osteen, he basically leverages his special relationship with Jesus (I'm a preacher, you're the sheep) to sell books. I just have a real problem with that.
If you have a problem with him selling the book, just don't buy it. I bought a copy for a Christmas present today however.
As Brother Dave Gardner used to say: "Different strokes for different folks".
And for your information, Lakewood Church is a very positive influence in Houston.