Eindhoven, The Netherlands. Kind of like the silicon valley of Holland still with major tech companies around (Philips, NXP Semiconductor, ASML, Tomtom, Here) and a growing startup culture. Eindhoven University of Technology is a major force in e.g. Solar and rent for a centrally located appartment will be around 1000 Euro. Train connections to Amsterdam and Germany (Düsseldorf) and a local airport with cheap connections throughout Europe.