Since you're already considering less convenient options than MCO... I have to suggest that you check out airlines that fly into Orlando-Sanford.
Allegiant Air is really low priced - and since you're renting a car already, it is worth checking to see if there is an airport near you that flies direct to Sanford.
There are so many flight options, and yes, you may find low prices... but remember to factor in how much of your vacation time is worth SOME savings.
When it comes to flying in to Tampa - you won't be ahead in terms of time, it will take a lot longer than Magical Express.
In terms of cost, you can think that it would take at least two extra hours in and out - so that's 4 hours total.
Plus the cost of gas....
Plus the cost of time....
You can really start to see how fast any savings that you would have realized quickly disappears.
Like I said, if you're open to other options - take a look at Sanford.
But know that your $200 savings with Tampa... or similar savings at another airport.... is very fragile!
If you rent a car and have an accident - imagine the time and energy you will have to invest in getting back to normal!