Passing up the chance for a bargain

I sometimes buy flowers in the local kosher store. There is a selection of daisies, mums, and carnation in modest bouquets for $2.99. These flowers are not only very affordable, but tend to live through at least 2 Shabbosos, unlike roses and other delicates blooms that last just a few days and cost far more. I picked up one today. When it was rung up, I pointed out an error. It rang up for just 13 cents. I know that these are supposed to be $2.99. But the cashier did not make the error; the person who had put the price label on had. It really did say 13 cents. So, theoretically, I suppose I was entitled to buy at the price marked. Still, I was certain this was an error on their part, and just as I point out errors in favor of the store, I point out errors in my own favor. So I gave up the savings of $2.86. I am not certain if that was lifnim mishuras hadin or required, given the facts that there was a taus on the store's part, but also a general rule that items sell for the price marked.