The size of a "new" lens may be problematic, but there should be plenty of choices.
If the lens/shutter is small enough, anything that fits 4x5 'should work" with the postcard format, and vice versa.
$100 won't get you a 135 WF Ektar, but it probly would fit as would a 135 Optar as mentioned above. I have a couple of small lenses in the pile for my Kodak #A folding Brownie and a salvaged K mount......and a lot of laziness, cuz I need to finish the bellows swap etc.
I have a few negs i shot on 122 long ago with the original Kodak lenses- RR s mostly and they can be sharp as anything, sure wish i coulda shot moving objects at 1/250. I just don't shoot on a tripod, or things that stand still, although I too have a nice looking Planatograph that tempts me.
Thanks for those example shots seawolf!
Good luck Doug