I am a new flute student (C-flute) and from what I gather from the books I'm using AND my own personal experience is that it's more difficult for beginners to learn to play low notes on a flute than high ones.
Many/most music stores allow you to test out an instrument before you purchase it. Try and find a store that carries an alto flute and give it a shot.
Playing an instrument that you would enjoy may be more rewarding and fun to learn than an instrument that you have absolutely no interest in. If the idea of having to play a c-flute before an alto absolutely kills it for you, perhaps you could skip the drudgery of the c-flute and go for what you want to play.
However, since more people play the c-flute than the alto flute, if you have any questions, it would be much more difficult to get answers specifically about the alto flute.