Wouldn't work for me, I don't shop that way (or at least, not the way you describe).
What I do is have a running list of things that I want or need. But what I actually buy depends on what is on sale, what bargains show up, how soon I need something, and sometimes there are substitutes or just wide open categories that I fill if the price and product are right. So my list is very very long, but only some of it gets filled from time to time. Some if it never gets filled, actually.
If I need something in a timely manner I might buy new, but if I don't I will often buy second-hand because I can afford to wait for that item so no point (usually) of paying retail.