Originally Posted by escog

I think one of the main points of this is to fool the various search engines. When doing price comparisons, Spirit will show up as cheaper. I'm hoping that the various search engines (e.g. kayak, expedia, etc.) will simply tack on the cost of carry-on luggage to whatever fare Spirit publishes. I'm pretty sure the vast majority of airline passengers take luggage of some sorts, so if there's a charge for both checked and carry-on luggage, it would not be unreasonable to simply tack on one of those fees to their fare in the search engine.