I got this handy-dandy little light probably 4 or 5 years ago. I love it! Just after I got it, when I went to quilt classes, people would ask about it. I happily told them how much of a difference it made to my sewing. Finally, I could see much better than before.
So many of us sew in spaces that don't have great lighting. I'd love a second floor sewing room with tons of natural light - I should dream on, unless I win the lottery or marry a lot of money! Having great light is important so that we can see what we're doing, and sew into the wee hours of the night, if necessary.
This light attaches with sticky stuff to the side or top of your machine. You can remove the light - you press on the level that's at about 1:00 (in the above photo) and you can slip out the light and cord. I only do this when I take my machine in for servicing. The sticky stuff hasn't come unstuck in all the years I've had the machine. I've also seen replacement brackets - I'd get that if I was switching the light between machines.
The light is LED and should last thousands of hours. I think I paid around $40-$50 for the light - I do know I got it on sale, so I think around $50 is the going rate. It's totally worth it in my opinion.