It's a long time since I took my bike on a plane, but on long haul flights to Hong Kong, Australia, N.Z. Fiji, The Cook Islands, several to the USA and Spain (from UK), I was never charged for taking my bike on the plane. Never once boxed it up or put it in a bag either - just removed the pedals. The bike always came off the plane undamaged, thankfully. At Hong Kong it was delivered to me very carefully by a very nice man with a trolley. Maybe with low-cost airlines things are very different but the "proper" airlines have always been great.
This may amuse some people.....On a flight into LAX I decided not to remove the pedals, but simply to take them out and screw them back into the cranks from the inside - to reduce the bike's width and avoid catching on other luggage. On collecting my bike at LAX, one pedal was conspicuous by its absence. I joined a queue of people whose luggage had also been "misdirected". There was a young female airline official at the front of the queue trying to locate the passengers' missing luggage by speaking to the baggage handlers on the tarmac via a walkie talkie. By the time I got near the front of the queue she was getting a bit frazzled. Then over the walkie talkie I heard someone say "Juliet - have you found that boomerang yet?"
I couldn't resist it. I leaned forward and said "Excuse me, Juliet: but just how do you lose a boomerang?" I'm afraid my British sense of humour was somewhat lost on this young American girl.
They never did find my missing pedal, but fair play, they paid for a new pair for me. Though cycling away from the airport to the nearest cycle store on a bike laden with front & rear panniers and my camping kit was a bit awkward!