I have the actual apple one, it's very small, and the plug is removable so you can get their international ones, but I took it out because it's the same generic power adapter as a few things I have, so I have my old dead printer's cord in it so I can listen to music (ok, you got me, by music i mainly mean the wishes soundtrack) to fall asleep and the battery won't be dead by morning because I don't use the sleep timer, that just lets me know i'm taking a long time falling asleep when i have to turn it back on...
so if you get the apple one it is possible to use an extension cord without the extra bulk of an extension cord. it's possible that if you have a laptop part of the power cord (before the converter block) would plug into it.
if that's not the goal then you'd be perfectly fine with another (cheaper) brand