It's made up of 38CrMoAlA and treated with nitriding gas treatment to improve wear resistance and hardness. And it includes free shipping from china, it's probably 5-10kg. And includes machined nozzle too.

Wood drill has continuous flight depth while extrusion screw has 3 zones. In compression zone, flight depth is gradually reduced to compress polymer.

Other than this, I think you'll have problem with finding reasonably straight wood auger drill.

With precision machine barrel and screw, screw will not touch barrel wall.

You can experiment with wood drill and steel tube but I doubt you'll get consistent diameter filament with it.

If you fancy making cheaper one for small scale/personal use, try this one:

https://medium.com/endless-filament/make-filament-extruder-f...