Not sure what you consider a reasonable offer on Priceline but the last time I stayed in SB I couldn't land 3 stars for under $70. And IIRC I got stuck with resort fees even at the 3 star places. On top of that, the 3 star hotels on SB would be considered 2-2.5 stars anywhere else (the buildings are OLD)

You can definitely get 4 stars in the Coral Gables/ Coconut Grove area for under $100 and will likely land in either the Hyatt Regency or the Mayfair Hotel, which are both very nice hotels and I believe both offer free airport transportation. The Mayfair is adjacent to CocoWalk which is a nice shopping and restaurant area.

I would just rent the car one way and avoid flying MIA to MCO. I'm personally biased as MIA is my least favorite airpot in the entire country. The car will be cheaper and you don't run the risk of the ridiculous delays that MIA is known for.