If I buy frames, they cost me $1.68 each if I buy a box of 100. To make a frame from non structural timber (where I have to cut around knots and defects) cost me around 80c each to make. If I use 1st grade timber, there is no saving at all. Access to free secondhand, untreated pine is a bonus. If you have the time, it is a worthwhile exercise, especially during the cooler months of winter. When you first start keeping bees, the costs just keep on mounting up. Buying boxes, frames, foundation, suits, extracting gear etc etc etc, burns a hole in your pocket rather quickly. Anything that you can make yourself helps to alleviate that issue. The major bonus is the satisfaction of doing it yourself even if there is no major cost savings. It is all part of the experience and knowledge gained in this amazing pastime.