Ours came out to about $1680 from Toronto for 1 week at Beach Palace in Cancun, airport transfers and direct flight with Air Canada. Our week is right before Christmas so rates weren't crazy high season prices yet, but they weren't low either. Unfortunately I couldn't really be flexible about the dates because I'm in school again this year and I had to arrange it for a week I have off, or wait until I'm done in May (which I wasn't willing to wait for before haha. Now I'm like oh shoot, it all came so fast ahhh!)
We also had some complaints about it being so close to Christmas and some people complained about the price, but as all of the ladies said above, the people that are going to come regardless will come through for you! We may have had a few more people had we waited until May or if we had chosen a cheaper resort, but ultimately we had to put our desires first because it is our wedding!
I'm not too familiar with Cuba but I think it'd be a bit cheaper than Mexico. Good luck w/ your planning! Definitely find a good TA