If you have access to 3D printers
$1 is awesome. They do take a while to print though, so don't wait til the last minute. We printed one at our museum. If your collections department is nice enough, see if they have replicas of any objects the patrons can touch.
With regards to way-finding, I suggest letting them know significant things (like stairs approaching, maybe walls at unusual angles). Also, talk to whoever is organizing the visit. See to what degree they are all blind and if they have chaperones with them.
I'm mostly blind and work at a museum. If you have any specific questions let me know.