Quantity   Component name
1 × IIC I2C 0.91"128x32 Blue OLED LCD Display Module Source: ebay, approx 2 €
1 × STM32F030F4P6 Mini System Board Source: ebay, approx 1 €
1 × DC 6v 100RPM long shaft Mini Micro Metal Gear Motor Source: ebay, approx 3 €
2 × 2pcs Axial Ball Thrust Bearing F3-8M 3 mm*8 mm*3.5 mm 3× 8× 3.5mm For RC Model Source: ebay, approx 1 €
4 × 20PCS 6x6x5mm DIP Through-Hole 4pin Tactile Push Button Switch Momentary Source: ebay, approx 1 € for 20 pcs
1 × 3ml 3.0cc Luer-Lock PP Syringe Accurate Measuring Source: ebay, approx 2 € for 10 pcs
1 × All the other electronic components Total value approx 5 €, from my stock or desoldered from various sources.