For immediate genetic information, pictures of morphs along with descriptions, get Kevin's book. It's got excellent basic info, but focuses more on the morphs and genetics. It's got a 101 section on how to do a punnett square and how to understand what you're figuring out with a punnett square.
The Barker's book, however, is WONDERFUL in the amount of information on care, ball python natural history, and loads of information about just the animals themselves. I seriously love my copy of the book. The running joke at work is how I ended up sleeping with it under my pillow for the entire week after I got it because I kept falling asleep while reading it...
You probably will want Kevin's book for the now, and the Barker's book once you can afford it. 
~jenny
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"Polysyllabism in no way insures that what you're saying is actually worth being heard." - Blake (an e-friend of mine)
"I have never made but one prayer to god, a very short one: "O lord, make my enemies ridiculous." And he granted it." - Voltaire