Cheapest way to go to Masjid-e-Nabvi from Madinah Airport

Can anyone please shed some light on the cheapest way to go to Haram (Prophet's Mosque in Madinah) from Madinah  Airport.

You can easily find taxicabs outside the airport, they usually charge 100 SAR to get to the Prophet's Mosque

They charge SR 30-50 to Haram from airport

There is a Shuttle bus service by Saptco between Masjid e Nabvi & Madina Airport that costs 15 Sar per head /one way ... The bus stop is in vicinity  of Masjid e Nabvi near masjid Abu zar Ghafari ...

Where is the bus station at the airport?