Tips for buying bread mixer that works effectively

A lady came from Ibadan to attend our monthly bread baking class and complained of her bread not rising, not smooth and not chewy and attractive.
When I asked her deeper on the type of mixer and how much she bought it, I discovered  she bought a single speed mixer at an exorbitant price, she did not know how to use it effectively and so she is not getting the right results.  This has been her challenge for two years according to her and this is also the challenge of many too.