I can tell you from experience that some audio books are real duds, but this one is great, with voices and sounds effects. AND, each story is about twenty minutes long. Sometimes, I get a full hour of Bub sitting and "reading" with these books.
(I get nothing if you purchase these books. Amazon doesn't even allow affiliates in California, so there.)
Edited to add: It appears the Thomas and Friends collection is also priced to sell at $6.40. I can't speak to this one personally, but the reviews are mostly positive.