One thing no one has pointed out here is that the "Lincoln Service" trains do not serve Wisconsin. So, to travel to Columbus, WI you will need to transfer to the Emipre Builder in Chicago. The Empire Builder is a once-a-day long distance train. The "piddly" fares you may have heard about, I'm guessing, do not involve a connection but are rather for "local" travel to places like Chicago or St. Louis.
I checked a hypothetical travel date for your route several months in advance and a non-discounted round-trip prices out at $84. So if the "$86" fare you found is for round-trip travel, it's about as low as you will get unless you qualify for one of the discounts mentioned here.
Keep in mind also that due to the need to connect in Chicago, the travel time on Amtrak between Springfield and Columbus, WI, will be significantly longer than the time it would take to drive between the two cities.