Is it usually the case that a one-way car rental will double in price? Seems exorbitant!

A little more on the search I'm doing:
one-way
ann arbor MI to omaha NE
minivan
2/27 - 3/1

By changing one option: return to same/different location, the price literally doubles from $85/day to $177/day. yikes!
I know this isn't a mileage charge, because the terms include "unlimited free miles"

I'm trying to figure out if there is some trickery going on here, or if this is indeed a usual scenario. Appreciate any help from your experience or tips on how to lower this rate.

Thank you!