I am looking for a way to auto tag items as "on sale" at parent level. I understand this can be done via script as "flow" might not be adequate.

We have a substantial catalogue of around 40,000 active SKUs (around 7,000 parent level).

The prices change frequently. Almost every day. An item is defined as "on sale" where the price is less than the compare at price.

For a selection of brands we want to offer a voucher but only where the item is full price and not on sale.

In order to do this, we need to be able to create a smart collection including only products from a defined range of brands where the product is AUTOMATICALLY tagged as "not on sale". If the tag changes, the product comes out of that collection.

I have tried using flow but flow has a limit of 100 products which is really annoying.

Can anyone recommend me a way to do this on a fixed price budget. I need this to be implemented across 7 shopify stores.