Cheaper alternatives to the Surface Laptop?

Depends. I don't know of anything that has that 3:2 ratio in the segment. The XPS 13 is up there, but it is also in the same price range. Same for the Spectre X360. The Spectre is a convertible and the XPS 13 can be one. The Spectre has the digitizer automatically whereas the XPS 13 doesn't come with a touchscreen automatically.

For a premium laptop that is thin, light, and made of high end material, the Surface Laptop is priced about where it should be.
 
I've been comparing some ultra-cheap Windows laptops lately, and $200-300 can get you quite a bit nowadays. Check out the CHUWI LapBook or Jumper EZBook. They aren't Core i5/i5 powerhouses, but for light usage... dang.