There are a few in the Eastern part of the US. I've bought Liters of 100mg/mL nic base from these 3: Wizard Labs in central FL, My Freedom Smokes in NC, and Nicotine Giant (used to be RTS Vapes) in SC.
The Wizard Labs nic base was top-notch in every way (smooth, tasteless, and odorless). It was the highest price of those 3 vendors though.
The My Freedom Smokes nic base was too "peppery" for my liking (quite a few others have posted about that, too), and they shorted me 180mL of the Liter I ordered. They couldn't tell me if it was nicotine, VG, or a solution of the 2 that had been left out. So I had no idea what the real Nicotine content was, without getting a nic titration kit and testing it! I gave most of the Liter away and have never ordered nic base from them again.
Nicotine Giant was RTS Vapes when I got 2L of their nic base. It was every bit as good as WL nic base, to me, and it cost less than theirs. Now, it's gone up in price to $64.95/Liter for their 100mg/mL nic base, but that's still less than WL, the last I checked on theirs. However, I think there are coupon codes for Nicotine Giant online. By the way, I'd put 1L of the RTS in a closet when it came, and totally forgot it was there for almost 2 years. When I found and opened it...it was still like new nic base...had no "off" smell nor taste to it at all. That's very unusual for any nic base that hasn't been kept in a freezer or refrigerated!
