@Lente I'm not actually looking for a light, but I was curious about cost, and then wondered whether it might actually be useuful to have. You gave a dollar amount, but without the country (American, Canadian, Australian dollar) - I assumed USD - out of idle curiosity I looked it up. It was interesting to discover that if I purchased it from the US Amazon I'd pay considerably less, even adding in $8.00 (USD) for shipping. When you referred to "mains" I thought you might be in Britain, but you gave a dollar and not pounds amount.
I found the price discrepancy enlightening. I've also heard about different prices being quoted to different customers through some kind of tracking system. I'm a prime member and was logged in when I looked.