I hate to be a pain, but in my tests, items in personal inventory are having no effect on the net worth calculation. In my practice game, I have the wish to be worth more than $25,000, which shows my sim's total net worth ($15,419). I can catch fireflies, make elixirs, pick up gems, cut gems, none of it affects my net worth. If I sold the items or donated the fireflies, that would show up, but holding them doesn't. When I buy an item, the cost of the item is subtracted from my worth, but the value of the item in my inventory isn't added back in...
Which I guess answers my own question? As long as it doesn't affect the bottom line, it's fair game?