One of the reasons I like photography is the ability to tinker with the process, much of which includes chemistry, but one has to understand that you tube videos are biased and rarely show all the mistakes and misfortunes suffered on the road to becoming an expert. Then novices come along and watch a lifetime of work in a 30 minute video and think, "Hey, that's easy!" I guess we all have to start somewhere, just don't do dangerous things alone....not something you want to learn the hard way.
"Pure" silver needs to be quantified. Kodak uses 99.999% pure silver for emulsion manufacturing. Ingot silver that comes from mines is about 99.9% pure. As described in "Making KODAK Film" 1st and 2nd editions, Kodak purifies the silver that they purchase. The impurities can make a huge difference in photographic performance.
the stuff is indeed expensive;it seems for goodreason! But still not worth the hassle or danger and nothing is more valuable as you or your family's health!
Years ago, based on a 19th-century recipe, I tried to make silver nitrate using commercial products, with very poor results. I tried again with a laboratory-grade product, and everything worked fine.
You will be able to make silver nitrate but it may not be of sufficent purity to be very useful for photographic purposes. The silver that Kodak uses for making silver nitrate is 99.999% pure. The silver used in coinage is not this pure. Kodak starts with high purity silver and adds other elements to produce the desired photographic characteristics in the produced elements.