My advice is not to buy a fixer, but to either buy one that someone else has really overhauled or one that does not need fixing. You will save money and get a better camera. The problem is that "parts" Leicas still command pretty high prices.
If you need to have one rebuilt, most major cities in the world (and some smaller ones) have competent repair men and there's no need to send it off to some strange place. Repairing a screw mount Leica is hardly rocket science, but I would not do it myself as someone here suggested -- it's still a pretty big deal.
If you shop carefully on eBay you can find a III series body for $180-230 USD and Summitar for $125-$175 USD or so, but you need to be patient. I just bought a Leica III for $140 USD in supposedly working condition, but we will see (that's about the rock bottom eBay price for a Leica working or not). I think the Summitar is great value, and while the Elmar should be cheaper I find that collectors drive the price of clean ones up too high. The Summitar has a better optical design than the Elmar too (that's not an opinion, it's so stated by Leica itself). Lenses can be cleaned up pretty well by a technician for about $50 USD, but I'd still try to find one without haze or fungus.
In my view most of the Canon Screw mount cameras are as good or better than Leica's and lower priced (but not cheap). They are clones, but not cheap clones -- they are built to high standards. Of the screw mount cameras I have owned, the Canon's seem to have survived through time in better shape more often than Leicas. Perhaps because they were used less, I am not sure.
I am sure some may take issue here with all these observations, but that's been my personal experience.
