Can't afford a piano, keyboard help?

I always loved the piano, from Mozart to Beethoven and always dreamed of being able to play Fur Elise and other clics. Unfortunately I don't have the money to purchase what I would call a traditional (grand piano) I guess. I need a less expensive alternative but know almost nothing about pianos. I see 51 key, 64 key keyboards and just want to know which one is the closet(in sound and key setup) to an actual grand piano. Also if you know of a particularly good brand that I can learn on that would be much appreciated as well. I don't want the keys to sound futuristic or electronic, I just want a keyboard that will sound as close as possible to a "normal piano". Thank you so much for your help this means a lot to me.