Amazon Books have a variety of crock pot recipe books ranging from just a few dollars.   E-bay also has a range of crock pot cook books that are both new and used. You will nearly always find what you want on the internet.

Looking around, I found that the price of the cookbooks are pretty reasonable with most being between $10-20. It all depends on how big it is, how it is presented such as hard cover or digital version, where you go to buy it and the quality of the contents. There are also sites where you can create, publish and sell your own crock pot cookbook like Lulu.com so that's another good place to investigate if you like writing.

There is a parts and accessories auction here on Crock Pot Meals and if you don't see one you like then go to Amazon.com at last count there was over 188 crock pot cookbooks there.