The Sinclair Cambridge calculator range started in 1973. They were known for their stylish looks, easy functions, generous user manuals, but most of all, being cheaper then the competition.
With the basic version selling for £32.95 (£390 in 2018! = $500), this being cheaper than the competition, it shows how the value of technology has plumited.
The Royal Digital 5-T was a direct competitor to the Sinclair Cambridge, but cost 1.5 times more.