The airlines normally allow you one pushchair and one car seat per child, free of charge. When I moved to the Philippines, I was flying on my own in KLM business class with 8 suitcases and decided to try it on by bringing two LARGE buggies (really big offroad 3 wheel fancy things) and two car seats. They called over the KLM station manager at Humberside, and eventually conceded that I was within the rules, despite not having any children with me at the time.

The better airlines like Etihad and Qatar wrap the buggies in plastic at the departure airport (including Manila surprisingly).

So seriously, its no hassle. As other posters pointed out, some airlines (NOT ALL) will allow you to take the buggy all the way to the gate, and will take if off you at the gate and then provide it to you again when you arrive, but others don't do this. If I recall correctly, Etihad has complimentary buggies for use in Abu Dhabi.