This is the sort of thing you do when you know you want to backpack often, not the sort of thing first timers need to worry about... it's great advice otherwise we wouldn't repeat it so often. But I'll stick with rent or borrow until you know you want to really do this - and then, get gear that is WORTH GETTING.

A really good sleeping bag will last for years and years and be a great investment - for someone who will use it often. I repeated the "cheap sleeping gear" mistake a couple of times until that sunk in. I do not regret a single penny of the $500+ I spent on the quilts and pad and hammock I have now, because I have had them for several years and had zero uncomfortable nights with them. And one of my 20F down quilts weighs 22 oz, is reliably warm for me to the advertised limits, and packs down to about the size of a football. When we are saying a sleeping bag is too heavy and not warm enough - it's probably also going to pack to the size of a bedspread. It is absolutely worth spending bucks on gear that is compact, light and very warm, I am here to say - that stupid synthetic bag I started with was cold, heavy, and filled half the backpack, and was not worth the eighty bucks, no way.