If Ultra Mushrooms and Jammin' Jelly are too expensive in your late-game playthrough of Paper Mario: The Thousand-Year Door, then you should get in the habit of cooking up healing items instead. Cooking can be done with one or two ingredients, and it's a great way to use up "weaker" HP/FP-restoring items, such as the Peachy Peach. There's only one place where you can get Peachy Peach, but it's guaranteed every time. Since there are several powerful recipes that require a Peachy Peach, it's one item that you'll want to stock up on if you're someone who likes to cook in Thousand-Year Door.