In case of same kind of products with different tiers I think a value comparison would be awesome!
What I mean is lets take food for example.
We have 3 tiers of food, all giving the same stats, in this case lowering your hunger.
Now to be perfectly honest, it doesn't really matter which tier you use, there is no benefit of using t3 over t1, except that you don't have to eat as many of the higher tier food.
Therefore the most important thing to know when you buy food from the market, is which tier is the cheapest compared to it's stat!
To know that, we could calculate it, then show it somehow in the market, just like when you go into a supermarket and on the shelves there is the small text showing you the price per kilo, or price per item, we could show the price per calorie. (here I have to mention the units again we talked about earlier, so instead of giving you points, food could give you calories according to it's tier, and the food bar could change to calories instead too. Change the number accordingly as well, you could perhaps roughly follow the daily intake of people?!
And one more regarding the hunger, if we'd use it this way, it'd behave the same as the other bars, so when you take calories the bar would go up, as you lose them it'd go down.)
The cheapest number could be green perhaps, and just like in real life, this could be a small text value, shown maybe after the price itself?
What do you think