I have been shopping for one also. As Jim said a code reader is just that and if you want a scan tool that is capable of doing some of the more advanced diagnostic tests, such as in my case I wanted something that could do diesel diagnostics like injector buzz test and cylinder contribution you are looking at spending a fair bit more money that a code reader.
What I did find that looks good for the price of a code reader is a PC based system from:
http://www.autoenginuity.com/ that’s what I’m going with rather than spending a few grand on a real scan tool just for home use.