I recently became eligible for Medicare, and the prescription plans all seem to suck. Last year, I went with a mid-level plan (Aetna Silver Scripts) that would presumably be the cheapest for me. Once I was actually in the plan, it turned out that the one med I was taking regularly was going to cost WAY more than indicated on the Medicare website or Aetna website back when I was comparing plans and making decisions. It rather felt like bait and switch to me. I have ended up getting the med for a small fraction of the price through Mark Cuban's Cost Plus Pharmacy.
This year I went with the Wellcare plan that only costs $6.00 in premiums for the year. I've recently been prescribed a generic med which looks like it will be free under this plan, and I'll continue to get my other med from Cost Plus, but at least I won't be giving Aetna $36/month for nothing. I know that $36/month isn't much, but it frosted me to pay them a premium and then have to get my meds from another source. I guess they at least covered me for several vaccinations. At one point I was prescribed a generic that cost me $12.99 out of pocket with my Aetna plan, and the full cost without insurance would have been - drumroll - $12.99!
Bottom line is that it depends on the meds an individual needs, and it is always worthwhile to be aware of options like Cost Plus, Good RX, and Buzz RX (which is apparently a lot like Good RX). Good luck!