As you know, there are many factors that determine market value within a certain location. What I can tell you however, are the statistics that can help you identify whether or not the real estate you are about to purchase for investment is in line with the estimated values of surrounding properties.
In Outagamie county, for example:
Estimated median house/condo value - $147,185
Wisconsin - $152,600
In fact, another great resource are the Trulia Heat Maps, which will help you visually compare prices & popularity by state, county, city or neighborhood. These maps can be a great indicator of whether or not there is strong interest for people seeking homes in a given area.
I have included the link below, and wish you luck on your investment.