The news that Frontier Airlines is being purchased by the private equity fund Indigo Partners LLC may first inspire thoughts of travel deals galore.

Low fares just like Spirit Airlines! But wait.

Indigo, which until this summer owned a stake in Spirit, turned that friendly little Michigan-based airline into a harsh bottom-feeder based in Ft. Lauderdale. Spirit is known for poor customer service and sneaky fees, charging for everything from water to carry-on bags.

Indigo now likely will work the same “magic” with Denver-based Frontier.

Frontier flies two routes from Detroit — to Denver and Trenton, N.J.

A check of this week’s fares from Detroit to Denver clearly show airlines’ differing strategies. A round-trip, nonstop flight Nov. 6-11 on Spirit is just $128. Sounds cheap! But you also must pay at least $50 round-trip for carry-on bags (we’re up to $178), plus pay for checked bags and other indignities.

Delta is $176, plus checked bag fees.

Southwest is $176, and checked bags are free.

Frontier is $188, plus checked bag fees.

United and US Airways are slightly higher.

Here you can clearly see that passengers end up paying just about the same price in the end, no matter which airline you fly. It’s all sleight-of-hand hocus-pocus by airlines that hope you aren’t too bright with math.

In fact, Southwest wins this head-to-head competition for anyone with checked bags. Spirit wins only if you have no luggage.

On your toes, travelers. ___

Photo Credit: A private equity firm is looking to transform Frontier Airlines into the next fee-happy Spirit Airlines. Pictured is a Frontier Airbus A319-111 in 2011. Flickr