Spirit Airlines FREE SPIRIT members who book flights for less than $100 each way can earn up to 1,000 bonus miles for flights booked by April 15, 2014.

The cheaper your flight, the more miles you’ll earn.

One-way flights of less than $36 earn 1,000 bonus miles

One-way flights between $36 and $65 earn 500 bonus miles

One-way flights between $66 and $99 earn 250 miles

“We see an increasing trend in other airlines switching to an elitist frequent flyer reward system that essentially favors customers who have deeper wallets and can spend more money on their flights,” explains Bobby Schroeter, Vice President of Consumer Marketing. “Our FREE SPIRIT program rewards customers based on their loyalty and we firmly believe that the more money we save our customers, the more loyal they will be.”

Luggage fees and seat selection fees will not be included in the bonus calculation, which is a good thing because bag fees start at $26 for a carry on and go up to $100 when checked in at the gate.