Your guess is pretty much on point: Total BOM was around 16k€.

A not insubstantial amount (for me) and entirely financed out of my own pocket - 107-systems is a private team staffed with volunteers financed by donations.

I'd preferred to stay below 10k but at the end it was do or die ¯\_(ツ)_/¯ . Since you write of having participated at such events I suppose you understand ;)

The most expensive parts were the miniature hydraulics as well as the custom CNC milled parts, which were created using a service for the manufacturing of custom front panels (a plate is a plate). But also all the small parts start to add up: cables, connectors, batteries, power distributors, ...