15-20€/month gets you 1-3GB of traffic from a cheaper operator like 1&1. "Premium" operators like Vodafone start at around 30€/month for 1GB. Whether you find t

15-20€/month gets you 1-3GB of traffic from a cheaper operator like 1&1. "Premium" operators like Vodafone start at around 30€/month for 1GB. Whether you find that reasonable depends on what you compare it to (I'm used to 10€/month without traffic limits), but either way those traffic limits are nowhere near enough to replace free Wi-Fi for work purposes.