You're making the assumption that you won't be able to purchase a box of assorted screws cheaper than making the trip to the hardware shop. If you could purcha

You're making the assumption that you won't be able to purchase a box of assorted screws cheaper than making the trip to the hardware shop. If you could purchase an assortment of screws that essentially spanned the entire range of the hardware shop, you might change your mind. That could easily change.