There are a bunch of online stores that sell contact lenses. Apparently Google Shopping is a big driver of their traffic, so they compete heavily on price in the Google Shopping results. For example, if you search for Acuvue 1-day moist contact lenses 90 pack, you’ll see the prices start at about $40/box. That’s a great price.
One of the places I previously ordered from sent me an email yesterday about their amazing Cyber Monday sale, which turned out to be 10% off (not so amazing). But even worse, the base price on their web site was $75—nearly twice the price they list on Google Shopping! So even with the 10% discount, it’s way more expensive.
Looking at the URL bar, these are actually two different product IDs on their site. I’m guessing they expose the cheap one to the Google web crawler and hide it from human browsers, and vice versa with the expensive one.
So whenever you order contacts, I highly recommend going through Google Shopping. Even if they only give you the discount price on your first purchase, there are a half dozen or more companies to choose from, so that will keep you supplied for a while.