Good Luck. Don't forget to save some money for film.
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.
The body holds film and lens and opens and closes the lgiht hitting the film. The lens determines the quality of the negative/transparency provided the film is flat, the shutter accurate and the lens mount parellel to the film; most bodies, even the lower end do a decent job in doing their job. Many lenses are good but more important in the process than the body in delivering the quality.
I am not promoting either Leica or Zeiss glass. Both companies have had good to excellent. Look for the glass that you appreciate and like and then make a decision. Remember if on a budget, there is also the Leica CL that can use the Leica and Zeiss M mount and is 1st rate as a user body at a bargain price compared to an equiv. M body. I use the CL and after 20 years would not upgrade to a M body in lieu of buying a lens to use with it. Also, the is the Minolta CLE that is where Leica probably would have gone if it continued development of the CL.
1960's lenses are excellent and can get you into the Leica world at a reasonable price.
I owned a 60's 50mm Summicron for 11 years and believe me it was a fine lens...
but not as good as the 2008 Summilux ASPH that now goes with my M3 :whistling:
And now for the question you didn't ask : are you sure you can adapt to the rangefinder system? I did in 5 minutes but there are some people (incl. pros) who never could and who went back to SLR's...
If you buy lens that is not Leitz - you will always wonder "how would it be if I have Leitz lens..."
So you should go for the leica lens - and then you know - this is it, now my limitation is for sure just me :).
If anyone can tell the difference between a image taken on Leica glass vs and image taken on Zeiss glass they are more psychic than observant.