The Sinclair System 2000 amplifier dates from the very early seventies (perhaps a bit earlier) and cost just over £30 when originally sold.  This was very expensive for then.  The amplifier was pitched at the top end of the market.

The circuit uses 18 transistors.  The case is solid aluminium and measures 12x2x6 inches.  It is very compact.

Although a very expensive item for its time, the quality of construction clearly shows the hand built nature of this piece of equipment.  The equivalent amount of money would buy much better quality nowadays.  Other items in the System 2000 range included a tuner and some snazzy round speakers, all in solid aluminium cases.