Rodenstock Eurygon 40mm f/4 (nice shape) - $120 OBO
El Nikkor 50mm f/2.8 (new N version, made in Japan, nice shape) $40
El Nikkor 50mm f/2.8 (older metal version, with locking nut) $30
El Nikkor 50mm f/4 ( older metal version mounted on Beseler square mounting board) $20
Schneider Componon S 50mm f/2.8 ( with front cap, in Schneider case, clean and clear glass) $55
Schneider Componon S 8mm f/4 ( with front cap and locking nut, clean and clear glass ) $80
El Nikkor 80mm f/5.6 (older metal version, with Nikon front cap in CP-2 bubble case, fantastic clean and clear shape) $50
Rodenstock 80mm f/4 (slight dust, should clean well) $60
Also, several cheaper 50mm enlarging lenses available such as El Omegar by Rodenstock, Beslar, etc available, some are a bit dusty, but should clean up $5 each
Locking / Jam nuts also available (mainly 39mm size) , $3 ea.
If you need mounting boards, just ask...I might have some left for Omega D5 / D6, B22, Beseler enlargers