There are certain things that I don't afford myself on purpose, for fear of generating a taste for the finer (read: expensive) things. On that list:
Evoo.
1 liter of Tannina for 3.99-4.99 is fine by me. It's bold, yes, but I'm used to it.
Oyster Sauce.
I'm 100% sure that those 15.00 bottles are umpteen times better, and better for you. Problem is, I use it a lot, and if I liked it more, I'd use it even more. I'll stick with those 1.00 bottles of the LKK cheap stuff that the Asian grocers have on sale on the end cap once in a while.
Red Wine.
I love digging through the 4.00 bargain bins. Pop it open, let it breathe for an hour or so, and you never know. I've found PLENTY under 10.00 that kick @$$. Also plenty of 4.00 bottles that are better than 15.00 bottles. My current lower priced favorite - actually has been for 5 years or so is Mcpherson. Think they are an Australian. Their Shiraz is deelish. Of course, you do get some stuff that's hard to swallow, but not a lot.
My personal theory is this: A lot of people are sheep, and think that if something is more expensive, it must be good. I run a business where I use this theory constantly. I do pretty well. I have friends who I give this advice to sometimes, and they do well when they use it. I won't give specific examples, of course, but trust me when I tell you that it's borderline amazing. Marketing is a powerful tool. Sometimes, simply adding a few dollars to a price tag is GREAT marketing. Sometimes adding TENS of dollars to a price tag is even better.
Conversely, I generally can't settle for cheap (mid grade) scotch, white wine, soy sauce, or tequila. If I find a cheap one I like, however, I'll start using it religiously.
We cannot be friends if you do not know the difference between Mayo and Miracle Whip.