it is not my intent to talk to you in or out of any course of action, but I want to share my own personal experience in a trial run for acquiring a nitrogen cylinder (USA): I went into an Airgas store and told the staffer that I needed a nitrogen cylinder to supply gas for a Winekeeper that I intended to give to my significant other as a gift. I was told that I needed food grade nitrogen, and that it would cost a few more dollars but I did not quibble over the additional cost so as not to raise suspicions. The total cost with deposit for the cylinder was under US$300. It may be helpful to put on a happy face and have the wine keeper product page loaded on your phone so you can show the store. These suppliers are used to dealing with welders and other industrial tradespeople so for a layman to come in and ask for gas, it would be very helpful to have a backstory already intact. Whatever course of action you end up taking, I hope you think it through soberly, meditatively, and don't just make a rash, impulsive decision. Also, if you are serious about this, you will need to be patient and plan carefully. For the sake of the people who love you, try to get your affairs lined up beforehand, including a note (extensive if you're feeling generous), list of passwords and Internet accounts, and I suppose most of all you should have a legal will. If you have any excess money, make a choice between leaving it to a person or persons about whom you care or to a legitimate charity.
Edit to add: I decided on a "forty," or 40lb cylinder to make sure I had plenty of gas to do the job. It is about the size of a carry-on suitcase.
