Even if you put a flat $30-$50 fee, make it have limited validity (with an expiration date). Like you have in SIMs. Many foreigners buy throwaway SIMs on arrival. Most of these SIMs have limited validity. You can use the same concept here as well. It makes no sense to charge a flat fee for eternity. Also, coming to think of it, tying up with a SIM provider would be a great idea. In the same kiosk/booth, foreigners can purchase SIM as well as get a Cheq verified account. You can share a % revenue with SIM provider and not have to hire extra staff. The SIM provider would have all the necessary setup anyways for physical verification. Just reuse that setup.