Thinking about learning to play the Alto Saxophone?

I think the title says it all really. I've only ever learned to play
the drums but I never continued with it. I just never thought much of
it really. I'm thinking about the Alto Saxophone now.

Is it difficult to play and do you need sheet music or can you learn
by ear? Also, what is the best Saxophone you would suggest. Value for
money would be best

Thank you :)