You might want to consider these options to protect your M11:

• Lim's Design Genuine Leather Half Case for Leica M11: Features a CNC-machined 6061 aluminum base for structural integrity. Make sure to check the mounting screw tension regularly.
• TP Original Leather Half Case for Leica M11: This is a lighter option. I would suggest being careful with the bottom flap alignment to ensure it doesnt rub the camera body.

> @Reply #1 - good point! Features like the CNC base are vital for keeping the M11 body rigid. Just found this thread and I've been quite satisfied with the Gariz Design Genuine Leather Half Case for Leica M11 Black. It features a 6061 aluminum baseplate that works well for structural rigidity and heat dissipation. No complaints about the technical tolerances either, the fit is exact. What's nice is you don't have to remove it to access the battery or SD card which is a big win for workflow. Tbh it should be right around your $150 budget. If you want something lighter, the Kaza Deluxe Leather Half Case for Leica M11 Italian Leather is a solid bet. It’s handmade and the leather thickness is perfect for impact protection. I’m happy with how it handles. Since you're in Chicago and need it fast, check domestic stock so it arrives before your trip. Both work well for keeping that bottom plate mint.

I disagree with the others about metal bases, be careful as grit gets trapped. I would suggest any leather from Artisan and Artist.

• Saves money
• Much lighter