Many times we encounter clients who have an idea of what they want and would like a quick estimate. It is important to clarify that only a very rough estimate can be provided under these circumstances as there are many unknowns at this point. If you really want to compare bids you need to have a set of plans and specifications with finishes selected so that each contractor can bid apples to apples.
Even so, some contractors might give a low bid by excluding work they know is needed to win the bid. If it seems too good to be true, be cautious. If you receive a low bid you need to question what things are not being excluded to give such a low number. Respectable contractors are licensed and insured, which gives the client peace of mind.
As a homeowner, I understand the allure of getting what you want for less, unfortunately, in my experience, you get what you are paying for. Quality work, done with licensed professionals upholding all building codes can be expensive in Florida, but it is the right way to do it and in many cases, home insurance can be lowered by bringing certain elements in a building up to code.