My (Mexican) wife and I found Mercado Marlen this weekend, and I noticed there haven't been any recent posts - so here is my update.
They are both a Mexican market and taqueria. The market is great! Prices were very reasonable and there is an excellent selection of authentic Mexican food and treats - some things my wife had never seen before.
However, my favorite is the taqueria next door. The food there is very, very good - and according to my wife, very authentic. She even started reminiscing about 'the old days' in Mexico and how she would enjoy food very similar to this while traveling between towns. The prices are perfect, the kitchen staff is friendly, and the servings are plenty. I highly recommend checking this place out if you are in the area.