^^^

Yes, it's worth it to invest in decent lithium batts and a charger as the light will be significantly brighter. Personally I like AW brand batteries as they have excellent quality control and the 2600 18650 batts have great capacity. I would get the 2200 though as their capacity is quite disappointing. If you are on a very tight budget DX also has some, but do your research first. Last I checked the black TrustFire were the best they sold.