I am a violinist and teacher. When a student asks what kind of violin should I buy, I advise them to pick the price range they know they can afford, and try out several violins. Most of the time they end up picking the more expensive violin. They sound better and are easier to play. There are exceptions, of course, but on the whole, the more expensive violins are easier to play and have a better sound. A person can spend anywhere from $100 to thousands for a violin. Even when buying a violin for a beginner, I urge the parents to buy the best they can afford. Children are much more willing to practice on an instrument that has a pleasing sound, rather than one, that no matter what you do, it sounds terrible.... even when the teacher plays it!
As far as buying a more expensive sewing machine, I feel one should buy the best they can afford... and definitely try them out... as with violins, they are all different.