Check Lowe's and Home Depot's sites. Go to toilets and sort by lowest price. Go down the list until you find one with an acceptable user rating. The absolute cheapest are seldom worth it but may be if others have found them to be good. You can also choose to only show items in your local store on their sites.
Home Depot has least cost high efficiency Glacia Bay single flush 1.28 gpf.
They have many types. From cheap to expensive. How much you use it has a lot to do with cost.
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