It doesn't get any cheaper than this. Frontier Airlines is selling tickets for just a penny (plus taxes) on a total of 88 routes (counting both directions). After taxes and mandatory fees, fares are just $10-$15 one-way or $25-$29 roundtrip. There are also many other routes on sale for under $100 roundtrip.
Frontier even eliminated its online booking fee for these super-low fares so this is the absolute lowest price you can get on these flights. Bag fees are extra unless you can travel with just a small backpack.
The penny fare sale is advertised for travel on scattered dates in late August and early September.
Some routes will only have very limited availability at these rock-bottom fares and most routes are only flown on specific days of the week. Click on the fare details below for booking info.
Tickets must be booked by 11:59 pm ET, August 9, 2019, or while supplies last.
All fares are nonstop and work in the reverse direction as well.
There are many more routes available for under $100 roundtrip. You'll have to decline all extras to get the lowest price.
These fares only include one small personal item. Checked bag fees start at $30 each way when purchased during the initial booking. Larger carry-on bag fees start at $35 each way.
Seats will be assigned at random upon check-in for these prices. You may pay a fee to choose a specific seat.
Frontier offers the Works bundle, which can be added to any flight during the initial booking. It includes a standard carry-on bag plus a personal item, one free checked bag, seat selection (including stretch seating), priority boarding, flight flexibility, and refundability. This is a value if you want all of these amenities, but chances are you can get away with just adding what you need à la carte for cheaper.
Searching Frontier's site, I found a flight departing Los Angeles LAX on Frontier's inaugural flight to Las Vegas, Tuesday, September 10, returning from Las Vegas LAS on Thursday, September 12, for $29 roundtrip. There isn't an online booking fee (carrier interface charge) for this fare, and therefore, it won't be any cheaper at the airport.