Yeah, just find/buy each of those books separately... cheaper, and probably won't be hard. In order, it goes --
Callahan's Crosstime Saloon
Time Travelers Strictly Cash
The Lady Slings the Booze
The Callahan Touch
I'm you can find each one for less than $10 apiece new, and they're well worth the read. The first 5 or 6 are definitely my favorites.
"The truth of a proposition has nothing to do with its credibility. And vice versa."