i dunno what the going rate is in the US for them here that would command perhaps £600-800 depending on how rough it was a mid condition runner perhaps £800-1200, in mint condition, better than showroom.. £2000-2500 ($2250-2750) and yes missing correct leg-shield is an issue, even here where they seem more plentiful its a difficult part to source. as it was unique to that particular model the electric start version especially. well they did sell them from 1959 until 2002 in different variants here.. if you want a honda C series bike best to look for a passport 70. lots more spares available, was sold all over the world as the C70. there are even body panel repair sections available. the main thing with these bikes is rear frame rot, under the fenders, and rear shock mounts especially. it is one place to double check with a fine tooth comb.
The other option is to buy a brand new Honda C125.. as they now sell them in the USA as well as here again since last year.