my thoughts go to those handmade punch cards on pinterest wherein you must complete ‘x’ things before rewarding yourself with a purchase (e.g. read 12 books, buy a new one).
this would look like a ‘prerequisite tasks’ option below the ‘notes’ field, prompting users to create a to-do list. completed list items should be striked through and marked off and the wishlist item should remain in the ‘want’ section unless purchased.