I have a Westfield VBS4A which is my first bass, and I find there are no problems with it, I love the small body on it, it feels fairly well made and there's nothing wrong with the sound. It is perfect for what I'm doing at the moment. The price tag was stunning for what it is at just over £100.
However I can see why people would spend more money - better quality of sound, brilliant materials, better build. All of these factors can contribute in a live or recording situation dramatically making the overall sound of your band professional and generally more pleasant to the trained ear.