Las Pupusas offers one of the best values in food: $1.75 per pupusa, with filling options that include chicken, cheese & herb, bean and cheese, and mixed. Order two of these, which get served with a shredded lettuce salad and red sauce, and you have a really, really good meal for less than $5!
I haven't tried anything else on the menu (the pupusas are such a good deal it's hard to pass them up!), but I'm sure they will be just as delicious. The kitchen has a big window that allows you to see all the prep and cooking taking place. Food is made to order, so be patient as it's worth the wait. For value and quality, I can't recommend this place enough if you're in North Las Vegas.