The Nic I got was MyFreedomSmokes, but importantly, in the GLASS BOTTLES. It is more expensive, but the plastic WILL absorb air over that much time. A lot of DIY'ers swear by Nicotine River, but I don't have experience with them.
Nude Nicotine also makes bottles called "V2 Armour" that have a collapsable bladder in them. The idea is that you can withdraw your nicotine from the bottle with a hypo through the top resealable membrane, and the bladder prevents oxygen from displacing the nic, deteriorating your juice. IT IS UNPROVEN. Nobody has HAD a bottle of V2 Armour for that length of time yet.
God, I talk a lot. There IS a way to get nic REALLY cheap from MFS (Myfreedomsmokes) and make it convenient, and likely to last you darn near your lifetime. You would need argon gas, those little rubber corks with two holes like ya used in chemistry, some plastic tubing and glass pipettes. It would be OK to start with the CHEAP MFS nicotine in plastic. Just a few months ago, they had 200mg/ml for, if I remember right, about $30/Ltr. For those mechanically, scientifically inclined..
get glass 10 100ml bottles, or 17 60's. Stopper them with dual pipette stoppers. Run a piece of tubing from one to a jar of water (keeps air out) run another hose from the 2nd pipette. Squirt a lil argon in there to purge the O2 from tubes and bottle. Setup your 200mg nic (or 100) the same way. Rubber stopper, two pipettes, ONE of these MUST have glass or hose that runs all the way to the bottom of the nic, and 1 hose to hook to the argon. You can purge your nic when you put the cork in.
Sounds comlicated, but it's not. The point of the exercise is to slowly pump argon into the bignic bottle, to displace nictone from your supply into the small bottles, without letting oxygen mix into it. Once they are full, just top em up with a lil more argon, and seal.
Do NOT fear that sudden changes in the laws or rules will make nicotine shoot up in price. It will NOT. We are the SAME number of vapers using it, whether it is shipping to Cutwood, Ahlusion, or directly to us. DO NOT feed a stampede, or fall prey to gouging. If anything, the price should DROP. They may have to pump down a lot of LARGE containers into a lot of SMALLER containers for us, but the nic supply is there to feed us all, and many will NOT be diying, so there should be a SURPLUS of nic, if the hammer falls suddenly.