I don't know there @K3Nv2 , but here, usually products has a code in their barcodes. Almost always looks like a very small 3 or 2 or 1 next to or below the barcode.
If 3, it means there'll be another "display" of the same product later next week or month, meaning (2).
If 1 it means the product won't be available anymore after they're sold out.
So, of course you'll get products with the number 1 code, because it'll be cheaper than a product with a number 3 code.
You should look if there's something similar in the place you live. The code thing is a secret amongst cheap stakes, so most people doesn't know about this.
Example:
Well, I mean, there's digital tools that searches for cheaper prices and stuff. Even Opera Browser has a built-in extension that shows you the cheaper price. I'm sure every other browser has something similar nowadays. At this point it's K3NV2's fault if you ask me.
My experience with On-Line purchases must be very different than yours.
I use Mercado Libre which filters items by Price, Reviews, Reputation of Seller and other things. On top of that, it offers you discounts if you're a certain level and free refunds and free delivery.
You're telling me there's nothing like ML in your 1st world country?