Last week, Volaris started celebrating their anniversary and discounted flights up to 80% off the base fare. Initially, this was a one-day sale, but it has extended into a week-long sale. The promo is now valid for purchase through March 20, 2018, and is valid for travel through October 2019. Many routes are under $200 round-trip.
Volaris has a seat pitch around 29", which is comparable to Spirit, but their baggage policy is similar to the major airlines. On some routes, you may find better value on other airlines, so search other sites to see if the major airlines have lowered their fares in response to this sale.
To get these fares, you'll need to select the "Up to 80% off" promo or just enter promo code VUELA8 when booking on Volaris.com for travel through October 2019.
Many routes are only operated on limited days each week. You may have to adjust your travel dates to find flights. Click on the fare details for specifics. Tickets must be booked by 11:59 pm CT on March 20, 2018.