My family has been going to Cancun for years, and it's always been worth the $7 to $9 per person or so a burrito with chips and a drink costs. The most expensive item on the menu are the prawn fajitas at $9.50, and most things
The lines can sometimes be a little long, but they move quickly. While my family usually ordered takeout, it's quet enough to dine in, and usually not too crowded.
Cancun's regular burritos ($5.10) or crispy tacos (This restaurants big bargian at $3.80) with pollo asada or with carnitas are very good, but I reccomend the Pipian Mole burrito ($6.60), which is served with a pumpkinseed sauce. They also offer vegetarian options, although most are not vegan. My favorites from thier condiments bar are the strawberry and the avacado salsa; but then again I have low tolerance for spicy salsa.
Thier chips are decent, but If you order takeout, don't make the mistake of saving the chips for later: they get stale in one day.