There is a med called Welbutrin which can be prescribed for quitting smoking and it works really well. It’s also prescribed as an antidepressant so one of my smoker friends was on it for that reason and they almost completely quit smoking without even trying to. Of course, it is not without It’s sideeffects but among antidepressants it is one of the usually best tolerated ones. I’m on it for my depression now and the only issue I have is that it can make me really anxious, but I’m also on nearly the maximum dose where for smoking cessation you wouldn’t be taking anything close to that amount.
My goto is usually rock auto. Other places can be cheaper but nowhere else has everything in on place. If I need something quickly then I just go to my local parts shop.