Mount Your Prints on Door Skins
I have been using thin plywood for mounting prints. It gives a very nice effect but requires a bit of wood working tools and a dry mounting press.
The thin plywood is actually called Door Skins and is available from building supply stores and has a mahogany vineer. Cut a piece larger than the print and sand the edges at about a 45 degree angle. Mount the print in a dry mount press.
The finished mounting can be wall mounted using velcro fastners or used with a simple wooden block with a grove cut at a 12 degree angle.
I don't think there is any acid worry as the dry mounting tissue isolates the print from the wood and the old masters often painted on wood and they have lasted for a very long time.