Rental prices vary by market, location, condition of the building, whether you rent from the owner or through an agent. You just have to dive in and ask, maybe drive through some industrial areas and see what's available, but I doubt you'll find any space that's large enough with any amenities you'll need. Even though you're on a tight budget, its hard to do without things like a bathroom, private office or storage, loading door, air conditioning, high ceiling, and parking, for anywhere near $300/mo in Tampa. Also consider whether the area is SO industrial that you'll have trouble getting models to come over. (BTW, $300/month gets you a one-car garage - no amenities - in west LA).
You might also check out some local photo labs and see if anyone has posted a note (or post one yourself) regarding taking over a space, or has a studio to share. That was how I got into my last studio, and our sharing (space only, not our businesses) lasted 16 years over two different locations. Saves a lot of money because you obviously can't be there all the time, and you share on some of the big joint expenses. Of course you have to find someone you trust, which I luckily did on the first try. One of the other benefits of sharing, with the right person, is the opportunity to share ideas and problems, and sometimes (again, with the right person) some equipment. We happened to use the same brand of strobes, so over the years we were able to get buy without having to rent stuff as often if we needed more for a big shoot. The idea of getting into a co-op or artist's loft building is a good one, if such a thing exists in your area. Our studio was in a really old industrial park, in a nice area, which is why it was the first building on the block to be sold and torn down to build apartments.
You don't say whether you'll be doing the business part at that location (will you get mail there, have a phone, have an office, need a busisness license?) All things to think about and which will add to the startup costs as well. Unless the space was a studio before, you could have all sorts of expenses just getting it ready to move in with nothing more than clean floors and white walls. Also, don't forget things like utilites on top of your rent. Electricity, especially with a/c, can get expensive, and it would be unwise to open the place without liability insurance. Its expensive to be a starving artist.
Andy Pearlman (happily working from home now)
Andy Pearlman Studio