WHERE to buy Cancun - Havana flight package/hotel deals for a decent price?

Ideally on Mexicana and not Cubana even if price a little higher.

We are going to Cuba in June.

We are Australian citizens and there is no technical issue at all about that, unlike Americans etc.

I am sure we will get screwed for the ~$US90 each or whatever for "Tourist card" fees etc.

We can fly into either Mexico City or Cancun for same price from here.

Last time I was in Merida there were dirt cheap package deals on the street for a few $100 for flights/hotel in HAV which I booked.

I am sure there still ARE in CUN especially, but need to pre-book if I can so as we get times right as we have a tight time frame.

Also want a day at Chichen Itza etc.

Are taxis worth getting at airport, or is it worth paying the ubiquitous "transfer" fee each way?

Anyone got a lead for a reliable agent who can do this for us and take credit cards?