Here's a video I recorded about various Acorn computers and ARM chips.
CPU: MOS Technology 6502/6512 @ 2MHz
Graphics: 640 x 256, 8 colours. 78 x 75, 8 colours (Teletext).
Memory: 16–32 KB (Model A/B). 64–128 KB (B+). 128 KB (Master).
Interfaces: RS-423 serial, parallel, Econet (optional), 1 MHz bus, Tube coprocessor interface, user port, floppy port.
Media: Cassette tape, floppy disk (optional), hard disk (rare), LaserDisc (BBC Domesday Project).
Value: £20 - £100 depending on condition, and whether software, box and peripherals are included.