he freedom from the cord is the primary feature that is added in a unit with an expensive price tag. The battery-operated units are also more expensive, but this also offers you a full range of motion and allows maximum mobility. Moreover, the units which are more expensive also tend to have increased warranty lengths. In many cases, the warranty jumps from 1 year to a full 3 year-long warranty. However, it is not guaranteed that more expensive products can expect a higher quality of the materials. This is also not 100 percent sure that the quality of attachments would be the greatest. Still, you expect that the quality would be better as compared to the cheaper models.