Honda CD-175:
Honda CD-175 was in production from 1967-1979 which means Honda discontinued this model for over 34 years. Original Spares are really hard to source, thats why CD-175 have a very low resale value. Engine can be revamped with jugaar and make shift spares but if you want a tension free classic bike than ditch the plan for CD-175. Trust me.....I have one!
Honda CD-200:
However Honda CD-200 was in production from 1980-2004, so there is alot of spare in the scrap market and thats why CD-200 commands a higher resale value, infact you can still find brand new zero meter CD200 in dubai (2004 stock) for 11,000 DHS.
Honda CD-185:
CD-185 was in production from 1978-1980. Again this particular model is out of production for over 33 years. The good thing about CD-185 though is its spare compatibility to CD200. Therefore a CD185 can be completely revamped. As far as the engine of CD185 goes, it has a higher compression engine than CD200 which means more power but CD200 has a better fuel efficiency.
So if you can spent on a original CD200 then buy one or else CD185 is the next best thing.