If you are looking for an inexpensive (read as free) but really nice location, try South Pointe Park in Miami Beach. I am a wedding planner and I have had a lot of my client's ceremonies performed right on the beach or in the park located there.
It looks beautiful in pictures and you won't spend a ton on a location venue.
I can e-mail you some pics of past weddings, just send me an e-mail at Maisy@romanticfloridaweddings.com.
Start your wedding planning with deciding your wedding budget and then make a checklist. It will help you in getting an idea of how much you have to spend on each wedding stuff. So plan it accordingly. Once you have completed with the budget and start looking for your wedding venue side by side with other plannings like wedding attire, flower decorations, centerpieces, invitations, photographer etc.