I have another, and differing opinion--since you are a beginner, I would guess that you are not using either a collectible guitar or an expensive, luthier built model, and you are not a traveling, performing, musician, so you don't really need the (very good) cases that Mcmoo has described.

I suggest a gigbag--a soft nylon/cordura case, with a strong zipper, a lot of foam padding, strap handles, and, often, backpack type shoulder straps, as well. It is basically a backpack for your guitar, and a good one costs about the same as a backpack--

The fiberboard case that you'll find in your price range won't be much more than a glorified cardboard box, but the gigbag is intended for heavy duty use--mine(which has all of the above features) cost $29 (about 20 pounds) and has crossed the Atlantic four times this year as checked baggage,made several trips to California (either as checked baggage or in the overhead-it is way less bulky than a regular case, and with the backpack straps, I can keep it discreetly tucked behind my back and 9 times out of 10, neither the ticket agent nor the flight attendents say a word when I take it on the plane)--

Another nice thing, you find a wide variety of them on the internet, and shipping is easy and inexpensive, sans guitar, since they fold up(a regular case is the same size empty or full)--