Ok heres the deal, I've done a little bit of backpacking in the last 2 years, usually just 1 or 2 night type stuff in pretty comfortable weather (nothing less than 40 degrees). I usually just hike in running shoes, cargo shorts, t-shirt and fleece for when it gets cold. I don't have any real specific outdoor type apparel. For my backpacking gear I have a $40 Cuscus 5400ci backpack, a $20 tent from target, a $25 30 degree sleeping bag, and an inflatable mattress that I blow up myself lol.

This is my basic gear
backpack
tent
sleeping bag

So anyway I've enjoyed the few trips I've taken and would like to do some longer ones this summer... maybe like some 4-7 day trips. I'd REALLY like to do the wonderland trail in Washington. So now I'm trying to decide if I go on a longer trip which gear is the most important to upgrade. I know my stuff is ridiculously cheap and supposedly low quality, but for the trips I've been on its worked out pretty damn well! Besides some shoulder soreness, a little water leaking into the tent from the rain, tent stakes bending, and the stuff taking up a lot of room in my pack I haven't had any major problems. I've gotten lucky with weather though smile So if you were me which gear would you upgrade first and why?

My problem is its hard for me to rationalize buying some of the really expensive gear I see on this website. How much better is a $300 tent or sleeping bag than my $20 ones? I mean I have some extra money around to upgrade my gear, I'm must not sure it would be worth it. Of course I've never really had nice gear before or have been stuck in weather worse than a hard rain, so maybe I just don't know any better. Saving weight would obviously be nice...is it the lightweight material that makes the packs/tents/sleeping bags so expensive?

Basically I'd just like to know the key differences in the more expensive gear vs the stuff I have and which gear would you upgrade first if you were in my shoes. Recommendations more on the budget side please. Sorry if this has been covered before and thanks for your help!