While I am an ASHI member, it is not accurate to say that they are the only qualified inspectors. I know several good inspectors who are members of both NAHI and interNACHI. With all due respect, the best way to judge an inspector is not by his association (anyone can pay dues), but by experience and credentials - and even then, you have to find the right fit for you.
Some inspectors are very stiff and academic - and some clients prefer this "just the facts" approach. I prefer a more personal style with more client interaction and education. (My inspections are more like a 2 hour "This Old House" episode with your home as the subject.)
In the end, it's all about YOU and YOUR needs - so make sure that you find someone who will take time with you, answer whatever questions you have, help you learn how to operate and take care of your home (and the point about providing cost estimates is a good one!)
Here in PA, it takes more than $40 to be an inspector. You must be a full member in good standing of a national association, you must have performed at least 100 fee-based inspections, you must have E&O insurance, and you must abide by a code of ethics. It is a pretty low bar to be sure, but at least it is something. Again, I refer you to the blog I posted earlier for some other points to consider and questions to ask. http://activerain.com/blogsview/206184/How-To-Hire-a
Remember, you are a potential employer interviewing job appliacnts - put them through their paces and take the best one!