There is a worthwhile difference between the cost of commercial AgNO3 and making your own. I have been makiong my own for several months now, and getting a "whiter" product than any I have purchased already made. I save about 30% on the cost. One needs to shop for the best price for silver(not sterling). Also the cost of the nitric acid is all over the place.
My results, as far as silver emulsions is concerned, are totaly comperable to purchased silver nitrate.