Tropical honeymoon for under 3k is it possible ?

Looks like you are in Missouri? Southwest has nonstops from St. Louis to Cancun, so you can EASILY make that budget. I'd recommend going on the "southwest vacations" page and pricing out some combo deals just to get a rough idea. (I would not necessarily recommend booking that way though, it'll just be a good way to get a rough idea of prices. Historically southwest only shows hotels IN cancun and not outlying areas such as Tulum or Isla Holbox so it would probably limit your options).

I've done a week in that region of Mexico for $1,000 per person (including spending money) on multiple occasions. If money is tight you could always sign up for the southwest credit card and use the points bonus to get both your flights for free.

We are going to Rivera Maya for 7 days all inclusive for $2,300. We booked with AAA. Look at Southwest Vacations as well.

As others have mentioned, cruises are great options and tend to be all-inclusive. Also groupon has a lot of deals

I spent 5 days in Riviera Maya for about 2K for two people. Airfare and excursions included.

Our honeymoon is to Puerto Vallarta and it's well under $3k