I practice criminal law, so I could be off.
Contracts are about a "meeting of the minds." Obviously, since you can't disassemble a brain (actually, you can but it is messy) and see what is actually there, people can make mistakes.
When the party making an offer makes a mistake, they can be held to the mistake sometimes. For instance, if a widget is $100 and they price it at $95, that's not an obvious mistake. If they price it at $5, that's fairly obviously a mistake. My recollection is that the merchant can be held to the contract if a "reasonable" consumer wouldn't have known of the mistake.
The problem is you usually have to sue the company where they are located. That's a problem with online purchases.
Consult a local attorney. (Another problem is that this doesn't appear worth paying an attorney for a consult...)