If you do make your own sets, it's all about how you value the time you invest in making them! Buy all the right supplies and yes, it's about 1/2 of what you pay from most stores. But then add the time in to make GOOD sets, sleeving if you do, stretching, equalizing, and it's a several hour job for those of us that can. So it really becomes a balancing act of what you consider time is worth to you. I have made many of my own sets for many year, but I pick a no wind day and make sets instead of flying, Being disabled, I have the time. Many don't. Theresa's (TKS) sets might be a bit more, but she makes every one of them by hand, using LPG materials. I know, I've used her lines myself!! They are accurately measured, prestretched, use light bridle line as sleeves. and are ready to fly as is!
So like I said - it's a determination of what your time is worth to you if you decide to make your own!