The Microtan 65 was introduced in 1979 and was sold as a kit for a very reasonable price of £59.95 + postage (pictured advert is September 1980). The CPU is a MOS 6502 running at 0.75MHz. It has 1Kb RAM. Input was through a small keypad with 20 keys or via a large keyboard. Display was via a TV interface modulator.
The Microtan is a Single-Board Computer, and with its low price, was very popular for hobbiests to build their own case.
Alan has a very good Microtan website here.