A medline search for lysozyme inhibitors yields the following:
alpha- and beta-N-acetyl-D-glucosamine (GlcNAc) and its alpha- and
go have a look at the papers, maybe you can find a supplier.
I have no idea whether this will inhibit chitinase as well...
Institute of Medical Microbiology
University of Zurich
srohrer at immv dot unizh dot ch