I'd advise caution in everything, right now. There is no need to stockpile anything for at least a year and possibly even 3 years. Even when the FDA enforce whatever they finally manage to achieve without legal actions stopping them, the black market will take over supply of anything that isn't street legal. 12 or 15 million vapers is a market that can't be shut down even by the FDA, ATF, Customs, and everyone else all working together.
In the UK we just had solid confirmation that there are already more than 2 million vapers, and one-third have quit smoking (a surprisingly high figure that no one was expecting, even the optimists among us) - and these numbers were supplied by tobacco control so no one is arguing with them. In another three years that will be 5 or 6 million just in a little place like the UK. I can't see any way that the US will have less than double that figure, and three or four times seems possible - 15 million vapers is a tough job to shut down.
Please forget about petitions and emails, people need to get carloads of vapers and families together and camp out in their Congress rep's and Senator's office; keep phoning them; keep faxing them; keep mailing them. That qualifies as action - petitions and emails are a waste of time. Petitions go straight to someone who is paid to throw it in the bin, and emails just get seen by an assistant who spams them.
If you want to do something, then be aware that if it can be done with two or three clicks on a computer then it doesn't qualify as doing anything.
Join CASAA and donate to them.
If you want to stock up, then leave it for a year or so and then see what the state of play is.