The 35mm F2.8 Jupiter-12 in LTM will fit on this camera. You can find examples that are new-old-stock on eBay for about $70 plus shipping, less for used ones. It's a real bargain. The next step up is probably a Canon 35/3.5 or 35/2.8 at over $100. The Acall 35 F3.5 is also a good choice if you can find one - about $100. There are a few others (e.g lower spec'ed Komura). The Canon 28/3.5 is an outstanding 28mm lens ($160-$220 or so). The modern CV Skopar Snapshot at 25/4 is also a bargain. Expect to pay about $170 used.

The Russian Turret finders work great, are inexpensive, and even have a limited degree of parallax correction. They cover 28-135mm frames. It is a good match to the Leica IIIc.

There are many choices in 50's. The Summitar 50/2 can be a good deal if you search ($150 plus). The Canon 50/1.8 is also superb for about $120. The Summitar will significantly outperform the Elmar and is about the same price.