Forget about N or a gun, buy nitrogen, trust me. I already owned a gun and bought nitrogen later. If you fail with a gun, you will be in far worse shape. It happens much more often than you think. This is what changed my mind on the gun. You live in the usa, so your main expense will be the nitrogen. Cyberweld will sell you a nitrogen cylinder already filled up and ready to go for $120 shipped to your door.
https://store.cyberweld.com/shielga...MIsLXK8KKm3AIVjcVkCh020wdyEAQYASABEgL5LfD_BwE
Then you need a regulator. Although this says argon, it will also work for nitrogen. There are cheaper ones, but this already comes with the hose.
https://www.amazon.com/Argon-Regula...=8-4&keywords=argon+regulator+with+flow+meter
From here, you just need either an oven bag or trash bag, a sweatband to hold it on your head, and some tape to tape the hose in the bag. Under $200 for the whole setup vs $600 for N. Just as painless too.