Cheap airport-to-city travel comes down to the same shortlist in nearly every country: the public bus is almost always the rock-bottom option, the metro or suburban rail where it exists is the best blend of cheap and quick, express airport trains cost more for speed and comfort, and taxis or ride-shares sit at the top of the price range, several times the rail fare. Shared shuttles fall in between but eat time looping through hotel stops.
Timing matters as much as mode. Road options are hostage to traffic, so a bargain bus at rush hour can take twice its posted time, while rail barely varies. Late-night arrivals flip the logic: when trains stop, a night bus or a ride-share becomes the practical answer, and pre-agreed or app-fixed pricing protects you from arrival-hall opportunism.
The airport's own website is the most reliable single source, listing every option with current prices and schedules, better than most blogs. My standing routine: check for a rail link first, note the last departure time, price a ride-share in the app as backup, and withdraw a little local cash before leaving the terminal for the bus if that is the plan.