In Rune Factory 2, although you need to order all building expansions from Byron, it actually is Yue who offers the items that allow you to take advantage of the upgrades.
A new option will appear in Yue's Menu in the 2nd Generation, offering 'Bargains' to your character. Bargains are available only on Monday, Wednesday and Friday. If you ask for a Bargain on any other day, Yue will declare that she has 'sold out' of all Bargains. Furthermore, if you do not have a Workshop, you will not be able to access the choices in the Bargain Menu. If you do not own a Kitchen, you will not be able to access the Cookware Bargains on Friday.
It is Yue who will sell the Small and Large Kitchens needed if you wish to cook the Recipes learned in your Lessons at School. It is she who sells the actual Forge and Pharmacy bench. Yue offers additional storage space in the form of a new Refrigerator and Shelves that can be purchased from her on Wednesday. Finally, Yue sells all the Cookware in the form of the old Harvest Moon 'Utensils' and moreover, sells all six Makers as a set.
Without Yue's Bargains, you will find that your new Workshop is nothing more than a big empty Room!
All this information is included in my General Guide now but here is a little video tutorial about Yue's Bargains: