First, yes I do have housing I can show you. Should be able to post a pic of the units we use for our Greek's. I'll give that a try tomorrow.
Second, tough to tell without a better picture, seeing their plastrons, and just how big they are in relation to a hand. Regardless, if you are going to buy all three you'll need an enclosure that should be a minimum of 4' x 6', 6 x 8 would be even better. Each of ours has a 3'x 6' plywood constructed enclosure. Greeks are roaming torts and need a fair amount of room.
The best substrate I've found is a 30/70 mix of topsoil and play sand. It doesn't retain humidity, retains heat well, provides good footing, and it's easy for them to burrow into at night. These guys like to bury themselves 1-2 inches into the substrate so make it at least 4 inches deep. And make sure you use a ceramic tile to feed them on. It serves two purposes. One, keeps their beak filed down, and stops them from ingesting any but a very small amount of the substrate. Whether they are Ibera, Soussensis, Werneri, Floweri, or Terrestris they will all do well in this set up. We can talk heating and humidity later.
If you do get them ping me at ernie_j@hotmail.com and I can get you all the diet, lighting, etc. info you'll need to have them a long, long time.
Good luck.