... and head for the social science section, the introductory human geography textbooks will probably have sections covering some of the economic geography theories (along with historical, political, and cultural geography). I've been teaching this for a few years, and we've been using Knox and Marston's book -- which isn't too bad, in terms of a general introduction to trade and development. They also go into geographical factors on a micro/local scale, e.g. why certain businesses prefer to set up shop in particular areas even if it may actually cost more for them to do so.
http://www.prenhall.com/divisions/esm/app/knox/One bonus is that they put a special focus on globalization (a major issue in recent economic geography) and some of the older pre-1990s texts aren't as up-to-date on this.
Another caveat is that some of the classic theories -- like the demographic transition model and the accompanying evolution of economies through the primary (resource extraction) and secondary (manufacturing) sectors, up through the tertiary and now quaternary sectors, are being criticized by researchers because they were developed using limited data (from only some parts of the world during a possibly-unique time in history). So whether these predictions are universally relevant remains to be seen. Will the example of Western Europe during 1700-1900 apply to India in 2000-2100? We don't know.
Also, some ideas about the link between environment and human cultures employ environmental determinism, which was dominant a century ago but fell out of favor in the late 20th century because, among other things, it was often used to justify questionable social policies (e.g. "economic reforms in Africa are wasted because the climate results in a weak work ethic, so capitalism and democracy can't take root") -- and there's an increasing belief that geography and environment don't account for complex factors like colonialism's effect on societies. This is why writers like Jared Diamond (the Guns, Germs and Steel book mentioned earlier) tend to distance themselves from the old-school environmental determinists -- rather than proposing a single explanation, it's now presented as "environmental possibilism" instead.
Good luck! Feel free to DU-mail me if you've got any more questions.