If you qualify for a subsidy
HealthCare.gov is the most affordable coverage available, full stop. Medicaid is partially expanded (BadgerCare Plus covers adults up to 100% of the poverty level) in Wisconsin.
If you don't
Full-price marketplace plans are the most expensive coverage in Wisconsin. For healthy people, private PPOs on Cigna, Aetna and PHCS PPO are routinely 30–50% less. Wisconsin has no state individual mandate.
What's not affordable
Health-sharing ministries and indemnity plans look cheap until you have a claim. Ask for the out-of-pocket maximum; if there isn't one, it isn't insurance.
Wisconsin chose a partial Medicaid approach that stops at 100% of the poverty level, so there is a subsidy-eligible group just above that line — and a large self-employed farm, trade and small-business population above the subsidy range.