wow, I didn't realize it was so expensive to transport bikes. If you buy your own box/bag and package it up as another piece of luggage do they still charge you?

If I do want to put a different saddle or something on the stock LHT, do they charge me for the original, stock saddle as well as the new one? Can I ask them to keep the stock saddle, for example, and just charge me for the new Brooks saddle (or whatever)?