I tallied up the BOM and calculated the total price, and it's just under 13€. Most components were bought from Elfa-Distrelec, except the PIC, which was bought from Farnell.

One thought I had about this project was to make it cheap, which I think it is now. I chose to use RCA jacks for signal outputs. I don't beleive these jacks are commonly used in synth modules. RCA cables are easily found cheap or free in junk bins or flea markets and they should give the same signal quality as any other cable type that might be used.