I don't consider myself tight but do try to spend wisely.
However, one former colleague years ago was legendary. His car failed it's MOT on windscreen wipers. He went and brought some new ones, re-took the MOT, passed, then took them off, refitted his old ones and took the new ones back ...and got his money back.
When you could buy Ever Ready batteries in the cellophane wrapping, he'd buy a pack, carefully undo the packaging, use the batteries, place the old, same make batteries in the packaging and seal them. He'd then take them back and claim he'd got Çs instead of Ds...could he swap them ?, invariably they did. That way he got more for his money.
He had a mattess that was within a year of it's 25 year guarantee expiry...obviously he contacted them and complained about it' comfort or something...and got a replacement. Why wouldn't he?