Qualifications
While different states have different licensing requirements for appraisers, as of January 2015 all states now require a person to have a bachelor's degree in order to become a licensed appraiser.
There are many things appraisers have to take into account when creating a valuation report for a piece of property: the noisiness of the area (traffic, flight patterns near an airport, or the daycare center next door), the age and condition of structures on the property, and any restrictions present, such as a ban on wandering livestock.
So, great—there goes the free-range eggs you were going to get from your yard chickens. Appraisers must know every little detail about a piece of property in order to complete a full and fair report (source).
Since the whole college-degree-thing is relatively new for this career, there are no four-year schools offering a major in the business. This is your big chance to create a DIY major. Sure, that sounds scary, but it's not bad. First, look for colleges that have New School or design-your-own major programs. Then, work with your academic adviser to create your own appraising degree program.
We recommend taking classes in business law, computer science, land and/or property management, and maybe even some construction management courses just to make sure all the bases are covered.
You'll need to know exactly what your home state (or wherever you want to live) requires to get your appraiser's license. Additionally, you need to know how many continuing education units (CEUs) are needed. Check the Appraisal Subcommittee page for information in each state about getting certified as an appraiser.