Agree with Dean in his findings and suspicions, this one is/was real.....
After talking with the Platinum Customer Service agent who finally admitted these companies like Ticotravel buy blocks of tickets way in advance. I got a humbled Yes, when I asked, Obviously most of these were purchased in the time frame when ORD-SJO was $277 and $297.

There was also a short period when the prices were in the $327 range which is the reason you see some in the $340 range now. They are going fast and anything going out a few weeks or longer is now $15 higher than prices you can book on the web site.
Example:
I just checked 12/9 to 12/12 for a quick trip. Prices for the short layovers were 277.70 on Spirit, $440,55 on AA. A quick check of their individual web sites indicates Sprrit at $263 and AA at $425. Both with short layovers.. Also checked out a January and February trip with similar results.
Here's a tip, when you see a large increase in prices on your tickets a couple months in advance, higher than you have seen in the prior month, check out Ticotravel, might have some from the prior month left if they continue this trend....
Hope this clears up the mystery,,,,