I have found NZ sphagnum at several local greenhouses which carry supplies
for orchids growers so that would be one possibility. The local orchid
society that I belong to also usually has a small supply for sale to
members and so others so if there is an orchid society in your area you
might try them. If these options pan out, here is a list of sources of
orchid supplies which have NZ sphagnum; I got them from the AOS Bulletin.
OFE International, Inc
PO Box 161302
Miami FL 33116
Tropical Plant Products, Inc
PO Box 547754
Orlando FL 32854-7754
Tropical Horticultural Sales Company
PO Box 520038
Miami FL 33152
Ann Mann's
9045 Ron-Den Lane
Windemere FL 34786
Good luck and good growing,
john ford
jford@ruacad.ac.runet.edu