File a complaint with the Attorney General's office, Consumer Protection Division, in your state, if you want to pursue it.

BTW: Did they authorize you credit card when you went to purchase it online?

If so, make a print out of the authorization as well and include it with your complaint.

Many banks will allow you to see "pending charges / authorizations" if you log into your credit card account online.

Since they couldn't fulfill your order, it shouldn't go through as an actual charge even if they did run an authorization for $99.99. Many places will also send through a $1.00 authorization and if that approves, the purchase authorization follows.

I did get a 500 gb external HD for like $89 at Staples yesterday. Walked in around 11am and they still had one in stock (only two were delivered to the store).