When placing a template for a custom item into a .json file in SPT-Realism\db\templates\user_templates, all of the stats get implemented, except for the price. When placing the template of a custom item into one of the files that contain the templates for vanilla items, the price change does work (only tested with armor, since armor price is affected by the realism ballistics option, by the adjustArmorHandbookPrices() function in Traders class that gets run in the main file when modConfig.realistic_ballistics is True).