A light is a light. A $4 dollar light is better than no light. Don't let these snobs bother you.
Unless it stops working after only a week, like my first cheap light did... or not be bright enough at all, like my second cheap light... or literally fall apart on every bump, like my third (at least I could put it back together, but collecting pieces from the middle of the road every day got tedious). I finally learned the 4th time and got a $30 light that lasted me 8 years.