It's perfectly normal to not be satisfied with the first results of a costume you make. With some costumes, I'm never done working on them. Others take a few tries to get it right. Each time you work on a project, you learn new techniques and refine your skills. Sometimes taking another shot at an older costume can be very satisfying!
Often, when I run a cosplay panel and talk about sewing machines, Brother machines are my go to recommendations. Why? After more than 15 years of sewing and using many types of machines, I’ve come to really apreciate the quality they display across all price points and love the Brother products I own. From the low end to the high, they work well. They are feature rich machines with a number of affordable accessories and sewing machine feet available for them.