If this is the case, they probably outright do not want you as a customer.

Significant sales (beyond for excess stock clearance/discontinued items) exist largely to generate some excitement from potential customers and to lure them in to taking a look at the site/store and to hopefully get them to buy some extra stuff that's less discounted while they're there.

The actual on-sale item is potentially losing money for the business or at break-even.

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A person who's running a series of bots like this to track the exact lowest price on the internet for items over time and to always only buy at the lowest price it's ever been sold for....is probably the least likely kind of customer to buy anything extra that's actually profitable for the business.