I live in Minnesota, and in one of the neighborhoods, people bought their homes not knowing that many years prior to when their homes were built, there used to be a plant that produced chemicals that have since contaminated the groundwater, causing their property to loose most of its value.
Because I don't live in the Tampa area, I can't give you specific names of people to call, but what I would suggest is the following:
1. Contact a lawyer or a civil activist's organization in Tampa and see what your legal rights are.
2. Contact the Tampa City Hall and advise them what the home inspector did and did not do when he performed the inspection on your house. Something does not sound kosher.
3. There are companies in Tampa that would gladly come and fix your problem (of course for a fee) and if you look at the attached site, they have a complete explanation as to what the problems are regarding polybutylene plumbing. http://www.polybutylene.com/poly.html
Good luck.