I think some colours are just more popular and some no one wants. For me, black was cheaper than red, but in our kitchen, black fits perfectly. There were machines with different power ratings - so keep an eye on the wattage. More power is important, especially for bread dough. In any case, the Rolls Royce among kitchen machines.
That's what I asked myself at the time. I would say "better built"; no. I think it has more to do with purchasing negotiations. Colours that sell well are bought in larger quantities and therefore at a better price.