Hi yovwmon. :welcome:If you think you will use your new light a lot, by far the cheapest alternative is buying CR123's in bulk on the "net". You can get as many as you want, but probably would have to get like 20 or so to get a "bulk" price. I've ordered from batteryjunction but there's other places as well. If you think you'll just use it occasionally, then just get some batteries locally. Most of the CR123's will serve you well. They are all lithium, just will have a little different capacity depending on brand. Where I live, we have Lowe's Home Improvement stores that sell Surefire branded 123's in 2 packs for less than 5 dollars, which is way cheaper than you'll find them even at Walmart and such. Buying in bulk online will get you cells for less than a dollar each sometimes. Enjoy your new light!