I spent about $70 on good wool yarn recommended by my LYS fifteen+ years ago. I nearly choked at the time, but I’ve worn that sweater VERY regularly and it still looks like new. Bargain bin yarn sweaters have pilled and are now house sweaters. My commercial sweaters have been trashed or Goodwilled.
A dear friend justifies buying pricey yarns not by the end product, but by the cost per hour of the pleasure they provide. She gets to select the yarn, handle and enjoy it for hours while she’s knitting, then enjoy it again while she’s wearing it. She figures it’s very cheap entertainment!
By the way, if you buy all your yarns online, LYSs will be driven out of business, and you won’t have anywhere to go to fondle the yarns, see the real colors, select the needles you want, or get good advice, classes, and support. Buy locally!