I was looking at this site, where you can enter any any amount from the year 1900 and find what it's equivalent is in another year; it only goes up to 2018, when the latest figures are available. https://www.thisismoney.co.uk/money/bill...anged-1900.html
I have a Bell & Howell brochure from April 1964, and the price of a model 644 was £340; the equivalent in 2018 was £7,185.16.

In 1970 I was working at British Leyland and a list was put up of ex company cars for sale. I remember one man was interested in a Mini at £300, much less than the price of a 16mm projector. In 1923 when Bell and Howell brought out their first Filmo camera it was the same price as a Model T Ford.

The Bell & Howell 644 was always an expensive model as it was optical with magnetic playback and record.