I would not entirely count on the advice you were given. There are many pitfalls dealing with owners directly. First, I have seen numerous situations where the owners are not the real owners and they do not have the authority to rent out a particular property or worse yet, are out to scam a deposit from an unsuspecting individual. Additionally, some owners try to cut corners on getting the condo association approval (if it is a condo is involved) and tenant(s) subsequently get surprise notifications that they are "illegal" tenants. Some assoicaitons DO have the authority to evict a tenant under these circumstances. Lastly, some owners are not forthcomming in declaring that their property is in default either with the association maintenance or foreclosure. Either way any of these scenarios can become very uncomfortable for a tenant. Please bear in mind that not all owners will behave like this but you need to be aware of this. Generally, if a property is being advertised well below the average market value you need raise the caution flags.
There are many respectable management properties on the beach and some that are not. Before making a decision, check with various posts on websites such as Yelp or Miami411 to name a few. Your best bet is to use an established Realtor who knows the area well. Remember, they are licensed and have a responsiblity to be on the up and up with you. Most importantly, agents are customarily compensated by the owners, thus the tenant does NOT pay any commissions. The only fees that a tenant normally is responsible is for a application for a condo association or appartment building. Applications normaly are about $100 per person unless the tenants are married.
I hope this helps.