The last line of the description - "This item is one roll of 120 format roll film." - does not appear on my screen unless I click on the "More Details" link.
In most cases it is not the law that a retailer must honour a mistake in an ad, because an advertisement isn't considered as an offer, but rather an "invitation to treat". In some cases there are local laws that do require such a price be honoured, and many retailers have a practice of honouring them, but that is a business decision.
Intentional "bait and switch" techniques are illegal in a lot of jurisdictions.