which is the best way to get from miami aerport to tampa and how much is it?

Try Uber. If you have their App, you can figure how much it will be.

I use mega bus to travel between Tampa and Miami... Can be as low as 1 dollar depending on when you buy your ticket. I haven't paid more than 25 each way so far.

Tampa you have options from $20-100

Amtrak is around $50.00