If you have no local music dealer to help you, try internet firms such as Sheet Music Plus or maybe helpful folks on the phone like those at University Music.
To locate octavos in the wake of mergers: Shawnee now carries my Mark Foster titles, Theodore Presser carries Coronet, and Alfred now holds Lawson-Gould, H.W. Gray, and CPP-Belwin!
Permission to copy "out of print" works held by Alfred can be obtained quickly for a modest fee. Others are available elsewhere; for assistance, please email me.
Some used print editions of my choral music are offered at reasonable prices by the efficient and reliable folks at The Music Library.