wine sales

[Bonita]

There was a wine display at the supermarket for $2.99 bottles of merlot, cab and chardonney regular price $8.99. At that price I took a bottle of each figuring it's not much of a gamble. Why would supermarkets offer such sales? The label didn't offer much information except "Robin Brook". I looked at the back for that colorful discription most wines have, but there wasn't any except for Bottled and vinted by Robin Brook vineyards California. Is anyone familiar with this.