I would not buy one from a stranger. I MIGHT buy/get one from a close relative if I were really in a pinch. But even then… I’d perhaps use their electric base but I’d still get my own brushes. It’s true that the expensive part is the replacement brushes. I definitely push mine past the 3 month mark. There is an illustration of what to look for when you need to replace. I bought the original electric toothbrush from Costco when it was on sale (I’m on my second one), and I buy replacement brushes when they are on sale, even if I don’t need them right away. Been using it for 15 years or more; gum recession has improved, plaque has improved. Mine is Sonic Care. So was the previous one. This one has a whitening feature.