Don't know. WL is a company I trust and widely regarded as having clean and consistent nic. The owner is a chemist. Based on reports, some others might have less consistent product. If you're willing to pay, you can get VapersTek -- but you're certainly paying a premium. I think WL is a good starting choice. They also sell 12mg, 18mg and 24mg allowing you to pick your strength, mix with flavors, and vape.
LD, I like your sig: "I might save some money next year..." LOL