> the monthly payment is about 1/4 of what I was paying for health insurance before I was eligible.

Maybe not, if you take into account the >$500/month subsidy of your Medicare Part A benefits (assuming you had the minimum number of calendar quarters paid in). And your Part B payment (the one usually deducted from your Soc Sec payment) is also partly subsidized unless your income is high enough to trigger IRMAA adjustment.