What is the estimated cost of BSA bantam mid 1950s?

In August of 1961 I purchased my first motorcycle, a 1961 BSA Bantam D1 125cc. This was bought new in Jacksonville, Florida from (at that time) Rick's BSA dealership. The price for a 1961 BSA 125cc Bantam was $269 plus sales taxes. The motorcycle did not have, nor have provisions for a stop light, only the single filament tail light was used. Using this as a guide, I would then assume the mid 50's price would be in the lower (US 200) dollar range, perhaps near $225 US dollars? The 125cc cave numerous transmission woes, was traded in for a 1961 175cc Super Bantam, the retail for that best I can remember was $359 US. Therefore I would assume the D7 Super Bantam to be in the lower $300 US dollar range in the mid 50's. For yeards I have searched for either a 1961 125cc D1 or 175cc D7 Bantam. I trust this will assist in obtaining a suggested retail price for the mid 50's D1 and/or D7 Bantam.