Chinese lens manufacturer Mingjiang Optical (also know as TTArtisan) has announced this week a budget-friendly 50mm f/1.4 lens for M-Mount.
TTArtisan lenses (sold at Amazon and eBay) are made with metal, aviation-grade aluminum, anodizing process, fine sandblasting on the surface and all the controls run smoothly.

Technical Specs:

• Focus length: 50mm
• Filter size: 49mm
• Max aperture: f/1.4
• Min aperture: f/16
• Frame type: full-frame
• Focus type: manual
• The closest focus length: 0.7m
• Diaphragm blades: 12pcs
• Optical design: 10 elements in 8 groups
• Weight: 399g

Here some sample pictures:

The TTArtisan 50mm f/1.4 will be sold at $370.
More info (in Chinese) on TTArtisan’s website.