My opinion for what its worth.... I do all the findings, etc myself out of sheet, everything I make is out of either sheet or wire, apart from small chains which we buy and of course the clasps and butterfly backs for earrings. I make jewellery as a hobby as I am retired now, although I do go to craft fairs once or twice a month during the summer and every month during the winter and undertake a few commissions as well. People that make jewellery for a living have to have a different prospectus on the whole thing, if they dont sell, they dont eat, so they have to make the decision whether to make and put a huge price on it, (which people may not buy because of the high price) or buy in some of the findings so they can make more and probably sell more.
I expect on commissions, the people who use bought-in findings will make their own as they can price accordingly, but for everyday stuff I dont blame them. Just as a comment on the subject - one of the craft fairs we go to, one stall has all "clip it together" jewellery, so the same ring is in 100 different colours, dont think he even solders, he sells rings for about £20 each, we make and sell rings for about £25 depending on how much the stone is or if there is a stone in it, I know its cheap but we cover our costs and make a small profit. For more ornate jewellery we obviously charge more, but I dont think we have anything over the £50 mark.