At first, I would present this extension box as a kit with all parts included.
But I'm sure you folks out there have plenty of resistors, capacitors, etc.
So it would be wiser to present only the difficult parts and PCB.
And even if you have a spare small stone phaser you can save money by removing the CA3094 ic's. They cost 35 euros, since they are collectibles. I still can order them with my electronic component supplier.
So here are a few prices :
- A professionally made PCB with solder mask and component layout : 60 euro
- 8 miniature relays : 14,6 euro
- "hard to find" ic and transistor package with CA3094 : 40 euro
- "hard to find" ic and transistor package without CA3094 : 5 euro
The rest are normal components you can find everywhere
If you are intrested in the whole package, the estimated price will be 170 euro.