How to handle 'Alternative Item' valuation in BOM?

ERPNext Manufacturing
1

We have a chemical product that requires a special glass bottle.

Our supplier has two suitable alternatives at different prices.

I created a template with variants product Item:

  • Special Bottle
    • Style A - $1.23
    • Style B - $4.56
  1. Do we need two different BOMs?
  2. Do we specify the template rather than a variant? If so, how is the BOM valued?
  3. What criteria does one use to decide between “Rate Of Materials Based On”: Price List or Last Purchase Rate or Valuation Rate?

This is our simplest case.

We have manufacturing input Items with M x N x O variant attribute criteria so getting this right in the beginning will save a lot of time down the road.

Where can I read guidelines on how the valuation rate should handled?

Thnx