Each Rescue or club has their own set of rules. Some charge a re-homing fee, some don't. If you are in California, most of the chapters of California Turtle & Tortoise Club have sulcatas at one time or another. I don't believe they charge a fee.
If you see on Craig's List or someplace like that, that they have a Sulcata for "adoption," they usually mean that they have one for sale. The fees on sites like that are usually in line with what you would buy one for in a pet store.