Nobody except bulk commercial manufacturers needs pure nicotine, it's as dangerous as cyanide. What you should use is ex: 60mg (or 100mg for the more experienced bulk DIYer) base liquid, which is unflavored PG or VG with nic, for dilution in your DIY e-liquid.
But since the FDA have just received another major setback in court, it's unlikely we need to worry too much for another few months at least. And you will have plenty of notice here on ECF if they succeed in their next ploy, whatever that might be. Relax.
To be honest, your best bet is to simply keep a good supply of commercially-made e-liquid, as it will be built much better than you can manage at present, plus DIY has risks for the inexperienced as you are dealing with concentrated toxins and there are safety issues.
And to repeat: nobody needs pure nicotine, it's far too dangerous unless you are a qualified chemist working in a fully-equipped lab. At the very least you need a fume cabinet to handle it. Would you brew up cyanide mixtures in your kitchen? Probably not.
No need to worry about the FDA for a while.
. This is from my experience, regarding the 510 and the eGo, both of which I use every day. I have the joye 510 with the PCC, and an eGo passthrough, the one with the battery, you can unplug and vape. I use the smoktech 1.5 dual coil cartos, on both, and for almost a month have had no problems, both vape great and are still kicking. Most of the time I have 18mg tobacco in the 510, and use it when I have a craving, and the eGo is my main vape, with whatever flavor I have mixed that day. I've been DIY my juices since I started and it's not that hard, if I can, anyone can. I use Easy E-Juice calculator, so I am able to mix to whatever level nic I want, right now I'm down to 14mg for the most part. That's the easy part, hard part is getting the flavor to come out right LOL. 
