A while ago, I contacted the local YMCA to feel out possibilities, and they are unable to accommodate Aikido training in their facility. That option is out. Kulhanek Sensei mentioned that mat space was at one point rented at Morris Dynamics, the judo dojo here, so if rental is the preferred option, that may not be a bad choice.
There are several gymnasiums here, so that's also an interesting idea. Thanks for hopping in the thread, Ron!
Josh, I think it would be pretty great to have a dedicated Aikido space, its own building, but I don't know if that's realistically doable. I don't know how much local support we would get, if the old students would come back and support the dojo or whatnot. I would imagine the cost over time would be less than renting, but the upfront cost would be harsh if there wasn't membership numbers to support the purchase of a space. However, as you mentioned, our market down here is ripe with commercial realty options. There are strip malls on the west and north sides that have closed and are since renting commercial space in one of their many building areas, and I would imagine that would be a cost-affordable option for a smaller space. There are open "office" spaces aplenty, as well. But you really should definitely check out the scene whenever your down here.
You mentioned long-term financial maintenance. I think the most difficult thing is in this case, as you said, is membership support at times of low enrollment. I don't know if any other dojos have done this, but has anyone had any luck with, or heard of, offering local students of other martial arts (at other facilities) a discounted rate for Aikido instruction? I know in the beginning this is how it was at Morris, but how about outside of that? To other local groups? I'm thinking go into a place, do a demo, explain how Aikido can contribute to their martial training, and then make the offer of a discounted training rate. Even though it won't be as much as standard membership, a bunch of discounted students are better than no students. That could be something that would definitely help a dojo, low-enrollment times or otherwise.
My .02 today.