It's pretty easy to buy brand name lithium primaries in lots of places these days. All of the major on-line light stores also carry cells as well. My grocery store sells AA and AAA lithium primaries, but unless they are on sale they are not that good of a deal. Amazon sells all the sizes, and Walmart sells the AA, AAA, and 9v, but I don't know about CR123As from them. Most of the farm stores carry the AA and AAA cells, and occasionally have them on sale for like $1.50 each.
If you have questions about the quality of any off brands you run across HKJ has great reviews of pretty much every cell on the market. It is worth looking them over before you buy.