I have used 50mm Summicron and Summitar lenses. Honestly, the lens is not the limitation to how my pictures turn out, and in my prints I don't really wonder which is which. That's 16x20 prints.
I also use Voigtlander Nokton lenses, in 35mm and 50mm, and am just as happy with those prints as I am with the Leica glass. They are not as well built, so probably will not last you as long. But, they are damned fine lenses, and it's a good lens to tie you over until you can afford your dream Leica lens. A 50mm Nokton draws a stunningly beautiful picture for you, and within your budget you could find two used lenses, like a 35mm and a 50mm, which compliment each other nicely in different shooting situations.