Free: Contests & Raffles.
I'd try to borrow gear to begin with. Yes, you don't need to spend thousands on gear to start with, but the reality is that lightweight gear thats good kinda costs $$$$$$$$$$$$$$$$$$$$$$$$$$$$... its pointless, in my opinion, to buy a $100 sleeping bag, a $50 dollar sleeping pad, some $150 pack and a $100 tent to end up figuring out that you enjoy it. I don't know if you've checked the used market on stuff, but the cheap stuff holds value terribly... and thats if you can even find a buyer. You'll be lucky to sell the stuff back for $100 bucks total.If you don't have anyone to borrow from, another alternative is buying used. You can find things like ultralight tents, packs, bags, etc that are already at used prices. Buy it, try it, if it doesn't suit you sell it back for little to no loss.A third alternative is buying yourself a pack, and renting the other stuff from REI. The downfall is that all of the stuff will be heavier than you want... but at least you're getting out and trying it out before taking the plunge.With that said, I echo kselkhunters #1 - get out there this summer and try backpacking in general. Hike in to some lakes with fishing gear... it makes for a fun evening, and bonus of maybe having some fish for dinner.Another reason I push buying used is that inevitably you'll try gear that just doesn't work for you. A lot of things like packs, sleeping bag/pad, tents, etc. are very personal... some guys are totally fine climbing into a coffin at the end of a day with nothing more than a CCF pad and their rolled up jacket as a pillow and get the best sleep of their life. Other guys like an actual pillow and an inflatable pad... for the most part, this isn't something you can know beforehand... only through trial and error. This is also why there is a huge market for used gear... this goes from packs to tents and even water filtration.