If you have a little time to really look hard for good deals on CL. You can scour their listings not only for racks and things for sale, but also bikes for sale that have racks on them. Then all you have to do is buy the bike, take off the rack, then re-sell the bike for about the price you paid. Ta da, free rack, well kinda, depending on how much you value your time. If you can buy the bike right now and hold it until mid summer you can even make a profit on the bike.
Next thing you are going to need are probably panniers, those might be really tricky to get a good deal on. So you have a few options, buy a cheap set of nashbar ones such as these,
click here. You can even find coupon codes to get 10% off of your order. With a set of these panniers and your stuff sacks you already have, thats probably all the new gear you would need. Thats assuming your camping gear is good, lightweight, small backpacking type gear. The waterproof panniers have 2,300 cu. in. of space. I back pack with a pack that holds less than that. Buy some bungee cords and strap everything else onto your racks, frame, handlebars, etc and go for it.
Or if you want really cheap, dont care what they look like panniers. Bucket panniers are cheap and easy to make,
click here.