Are all of your prints unframed, or do you have a mixture of framed and unframed prints that you want to display?
If I were in your situation, I would think about displaying mounted/mounted but unframed prints on the walls without plastic wrappers. Plastic sleeves do a wonderful job of protecting prints that are exposed to handling, but they do modify the appearance and impact of the print. Sleeves are probably best reserved for those prints that are displayed in bins.
What kind of walls do you have in your gallery? Do you have the ability to install something on the wall to which you could attach prints? There are two possibilities to consider. One is to install a rail of some sort to hold prints. I've seen plans for wall installations that involve a pair of rails, each with a rabbet, to hold the prints in place. Of course, that would require that the mounts all be the same size and orientation.
Another thought - here in the US we can buy a material called "homosote". This is basically a thick cardboard, typically 1/2" or 3/4" thick, and in 4x8' sheets. The attractive feature of this is that ordinary push pins can be used to attach mounted prints. The material comes in a fairly neutral gray color (probably closer to a 10% than an ideal 18% gray), and can be repainted if it becomes soiled. I have a sheet on the wall in my darkroom that I use to pin up work prints to stare at for a while before making final prints.
