I like the Lumintrail lights. The LuminTrail LTC-7043 is $20 and does a good job for simple rides from A to B. If I'm going a short distance I usually will use this light for my bike.

But what's nice is they also have a 3000 lumen headlight for night riders. A friend of mine is doing an everesting adventure and he picked up that light for the night rides.

They usually have some good deals and are available on Amazon too so prime members get free shipping. Hard to beat that.