One of the things often overlooked when compiling an emergency kit is a lightweight rain suit. If you're caught in inclement weather, it's important to have suitable covering to stay dry and ward off possible hypothermia. I was shocked to find that under 70 degrees, not only can you suffer from hypothermia, but death can even occur. Add just a 10 mph wind, and the chances of hypothermia rise dramatically.
Unfortunately, this is a product that "you get what you pay for". In researching possible recommendations, I found that the affordable rain suits didn't get stellar reviews. Complaints of tears and flimsiness were common. So your options are pretty much this: go cheap and replace it often, or pay more and get the craftsmanship that lasts. "Affordable" and "Quality" don't seem to jive when it comes to rain suits. There's nothing in the middle.
So if the expense is an issue for you, then I'd recommend you just go the Walmart route. Rain jackets run around $20-$30, and you can find the pants in the fishing department for about the same price. I've actually had the Walmart variety for a couple of years, and it is lightweight and easy to roll up and stick in my GoBag.
If durability and quality is what you're after, then spend the money and buy North Face. This product is dependable, lightweight and fully weatherproof. You'll spend anywhere from $69 - $109 per piece (jacket and pants are sold separately), but you will know you're getting a quality product.
The one thing you don't want to do is get caught out in the rain without suitable protection. The consequences can be uncomfortable at the least, and even life-threatening if temperatures drop. So don't waste anymore time --- save your pennies, be prepared and don't get caught out in the rain!