I spent £120 on mine (John Lewis own brand) and it does everything I need it to do and more. I have made curtains and cushions and even some clothes for my baby. You can get a basic one for sub £100, but it seemed to me that if you can stretch to £120/130, you get a lot more machine for the extra £20. You might be able to get a bargain in the summer sales maybe?
Good makes are Jenome ( who also make theJL own brand I think) , Singer and Brother. The woman in John Lewis Oxford Street was extremely knowledgeable and helpful when I was looking for mine.
They normally come with everything you need to sew basic things. You might want to buy some extra bobbins, and a zipper foot if you are going to do any dress making. Hope this helps!