Not sure if this is helpful, but we went to Cabo and that trip was EXPENSIVE. We aren't planning on going back to Mexico in the future unless it's a friends trip or something we aren't planning. It felt like we were stuck in our little tourist area (for 7 days) so after the 7th day we were ready to head home.
I am a travel agent. The longer you stay of course the more the cost would be. You definitely want to stay at an all inclusive property. If you are looking cost wise, I would recommend for Jamaica Grand Palladium and Riu properties. As for Cabo, Riu Palace or Pueblo Bonito properties. Cancun Riu properties, Grand Palladium and Royalton properties.
Southwest vacations has incredible deals. My fiance and I went on a trip April of 2018 through the site. Chose THE SANCTUARY CAP CANA in the Dominican (all inclusive adult only) and were blown away. We didnt spend a ton and the resort was beautiful. I believe they even have some great special fares right now. When you get on the site... go to vacations, and you can choose your region and work backward from there. We researched every resort they offered via trip advisor to choose The Sanctuary. And hands down... best vacation ever.