Shopping around: The battery edition

I found an old HP-20S calculator in my stuff when unpacking all of our crap. It's a nice little scientific calculator that would be a shame to put out to pasture.The problem was that the batteries have long since gone flat. This little fella runs on three LR44 batteries. The LR44 is a synonym of a large number of names for the same 1.5V alkaline button battery.En was running out anyway so it would be worth buying a set -- it'll last another decade.First she went to Bartell, a local drug store. These folks were selling them for a $4.29 each.Pass.I remember these as the cheap batteries you could get four for a dollar.Staples had the 76A battery for $1.69 each.Better, but pass.Amazon had it for $11 and change plus tax for a pack of 50 of them.Better still.eBay: $3.29 for 50 -- no tax, no shipping.Win! I now have a lifetime supply of these batteries for less than the cost of one from the drug store.Oh, and they work in the kitties' laser pointer too!  :-P