You don't have to spend a fortune! In case you haven't seen my recent responses to similar questions in the Backcountry Beginners section:

Home page of this site, articles in left-hand column--lots of info on gear selection, lightening up and several good gear lists.

$300 Gear Challenge --very recent and up-to-date; includes a number of alternate options that are still low budget, just not quite as low.

Dirtbagging and Deal Shopping

Mark Verber's Recommended Outdoor Gear--encylopedic treatment of the latest technology, although it is now several years old and could use updating. The main difference is that there's a lot more cuben fiber (but that's $$$!) in use, and supposedly water repellent down is now available. The articles include low budget options at the end of each section. There are also links to lightweight gear lists and low budget (but still lightweight) gear lists. A few of the links may be dead, but a lot of them are alive and well.

Actually, if you come in at about 15 lbs. for everything except food, water and fuel (and it sounds as though you will), you're in pretty good shape!

Except for a new insulated air pad (that Exped I keep bragging about), I haven't bought new gear for the past 4 years, and probably won't. And it's only the last few items I did buy (except the pad, which is heavier but more comfortable than what I had) for which I spent horrendous amounts of money to squeeze out the last couple of pounds to go from 13.5 lbs. base weight down to 11. I'm not at all sure that expenditure was worth it!