Alright hate to break up this party here, but the shoes that people are buying on discount are for a reason. It's not just that the styles are old, but that the shoes are made via an injection mold process to keep such a light weight, particularly in EVA. The water that is injected into the shoe as a by product of the process goes on to dry out over time, whether you're running in the shoe or not.
Essentially, your shoes expire over time even by just sitting around in your closet. That isn't to say that the shoe isn't going to feel like new when you put a new pair on, but instead of the 300-500 mile range, youre looking at between 100-300 miles. For this reason, all older shoes can be found for very cheap because they inherently are not as good of shoes as the full price retail ones. I'm not making this up, do your own research, but I'm well into the running industry and it's common knowledge among every company. If it wasn't true, companies wouldn't routinely try and get rid of a certain batch of shoes at a set time after they were made. The shoes that go on sale are often the current model year but an older colorway right? Well that's because all of those were made at the same time in the same factory, and they're reaching their expiration date when you're buying them.
As far as shoes like Adidas go, in my opinion they're a great deal, in that the process to make them has to do with essentially evaporating all of the small plastic pellets, making the Boost material. By doing this, they aren't susceptible to drying out like traditional shoes. The really unique, resilient feeling that you feel when you put them on stays that way for far longer than other traditional shoes.
You don't see them on sale for that reason very often, the shoes simply don't wear down in the same way and you aren't buying an inferior good. Again, hate to break up the $80 maximum gang, but this really is not made up and a detail that most people have absolutely no clue about that they really should