Newsman allow me to share some of my recent experiences as I just went through the same entire process you're describing. I'll try and give a pro/con from my perspective as I went round and round on which way I wanted to proceed. I'm here in GA as well, so our struggles are the same as well in regards to the lovely summers.
If you're going for a "ferm chamber" I would recommend finding a small chest freezer or mini fridge tall enough to fit your fermentation container. Here's why.
Full Fridge:
+ Pro - Space. More than enough room for one to two fermentation containers.
Con:
- For the purpose of fermentation, it's really not the most efficient use for a fridge.
- As mentioned above. The Freezer is actually the part that provides the cool air to the fridge. If you try to run your fridge at ferm temps (60+ degrees), it's very unlikely you'll maintain freezing temps in the freezer because the coldest air goes into the freezer, then the residual cold air blows down into the fridge. Hence why the coldest part of a fridge is typically the top back area because it's getting the direct blast of freezer air.
- Size. This may not be an issue for you, but being that I own two cars, no truck or van, I required a buddy's assistance to go get it, move it, and unload it.
This is essentially eliminating the intent of why you're looking at the fridge for the value of the freezer.
Small Chest Freezer
Pros:
+ Cheap. I found tons of these on CL for relatively cheap. 25-75$ listed price. Can easily be negotiated down to 50$ or less.
+ Size. You can get one big enough for 1 ferm container, it can easily be moved around with the help of another person, but can be manageable by yourself.
+ Availability. They seemed to be everywhere when I was looking for a 5+ cu. ft. one.
Cons:
- Raising/lowering ferm container is a major concern depending on what you use. It's the primary reason I'm moving to a better bottle carboy in the next few months. Raising and lowering a full glass carboy isn't impossible by any means. However, the day I screw up is going to be a bad day regardless if I get hurt or just have to clean up a ton of glass.
- Space. If you go with a smaller one you'll only be fermenting 1 5 gal batch at a time. May not be a problem for you if you do that or less. I considered buying two small chest freezers to be two independent ferm chambers so I could ferment at two different temps.
- Scaling. Where do you want to go in the future? Consider a bigger chest freezer if you see yourself doing 10g batches or have a reason to have 2 fermenting vessels in there simultaneously.
Mini-Fridge
Pros:
+ Size. Most people can pick up and move themselves. Always a plus.
+ Cheap. Like the small chest freezers. There's always an abundance of these available on CL.
+ Shipping. If you find a great deal on CL, eBay, Amazon, etc these can be shipped with relatively low shipping costs in comparison to a chest freezer or fridge. This can really expand your options and your shopping.
+ Glass doors available. There are alot of wine fridges on CL that will fit a ferm container with a glass door. Just a nice option of being able to see the fermentation happening. I couldn't find any during my searches, but I would of probably gone with this if I had.
+ Raising/lowering container. Simple, just slide the container in.
Costco sells the Danby fridge that doesn't have a freezer compartment.
Cons:
- Freezer compartment. Almost all mini fridges come with a freezer compartment now that will likely get in the way of the required height. If you're a DIY and comfortable removing that, some are easier than others.
- Compressor area. Most also have a small hump that makes only half of the bottom floor of the fridge actually functional. Depending on the size of the fridge and ferm container, this may or may not be an impact.
- Reliability. Mini-fridges tend to be more inefficient in power consumption as well as lifetime. For a ferm chamber, it's not that big of a deal because it's just going to run in short duration.
- Efficient. Mini-fridges tend to be less efficient at insulating and retaining temperature. This being the case it'll have to run more often, but shouldn't be a huge deal.
My recommendation is to find another standing chest freezer to fit your container.
Hope this helps you speed up your decision.
What size / type of fridge would you recommend for converting to a fermentation chamber? I'm thinking of going and getting a "Craig's List Special" rather than spending a lot of money. 
