These came out in 78 and were sold through the 80's. For some reason, inflation calculators for pounds sterling differ a lot, but looks like £22 in 1980 might be in the £90-122 range today.
Wikipedia says they could play these games,
- Tic tac toe
- Music machine
- Echo, a game similar to Simon
- Blackjack 13
- Magic square, a pattern game similar to Lights Out
- Mindbender, a game similar to Mastermind
And about the music machine,
The music machine game functions as a musical instrument; in this mode, each key is assigned a musical note, and sequences of notes can be recorded and played back. This makes Merlin one of the earliest digital sequencers as well as an early consumer-level electronic synthesizer.
This was my favorite toy as a kid!