A representative at Marlin also said they will match (in some cases, even better pricing) between tour companies...as long as it is the same day departure and same resort. She said that she did that for a couple - they saved $150. Now thinking back, she said they were able to fly out with Nolitours rather than another airline. Marlin and Nolitours are affiliated with each other. Go to both sites, you will note the star logo that is Nolitours' logo.
BTW went to the Nolitours' site last night and this morning - unable to get pricing for El Salvador past December. Just showing for November and December. That is strange..just a week or so ago I could get a price.