After one of the best summers in recent memory, the time for wearing a raincoat is back. From the lowest possible priced coats to the R.E.I. Co-op top of the line coats there is something out there for everyone. Thirty years ago on a beginners' backpacking trip in the gorge, the trip leaders recommended ponchos and garbage bags for use as impromptu raincoats. These work to some extent, but sometimes it's hard to see your footing with a poncho billowing around you in a good rainstorm. Also, your arms can get pretty wet, because they won't be all the way covered. With the garbage bag, you can cut out armholes and a neck-hole. But again, your arms will still get wet and over a distance, moisture could build up inside the plastic as well.
Do read the tags if you shop at a department store. Water resistant is just that, resistant but not waterproof, a poor choice for a long weekend in rainy weather. Consider what kind of camping or other outdoor activity you're doing. Will you be able to get out of the rain at some point? Do you have a stove for cooking a hot meal or cup of tea or cocoa? Or are you in a structure where you will only be walking a few feet to another sheltered area, restroom or car?
The invention of waterproof and breathable material has really helped raincoats to be a lot more comfortable. Attached is really great article from R.E.I. that compares the new types of raincoats and also gives some of the science behind the choices. Some of the really good coats cost in the hundreds of dollars, so it would be good to have an idea of what you want before you go.
Another option is reading the literature, but then looking for sales on the internet and at outlet stores. The list will show some of the choices that are available.