Do locals haggle at Mercado 23, or is the first price the price?

I moved here recently and I have been buying fruit and vegetables at Mercado 23, because someone said it is where people actually shop. It is busy and I like it, but I never know if I am paying the normal price or the new face price. A supermarket would be simpler, or I could ask a neighbour to come along once. Do locals usually pay the first price at the market, or is it fine to ask for a better price?