If you're a thrifty shopper, your best bet is this Coat. It's a great piece, while not very expensive.
If you can afford to spend a little more, look no further than this Armani Collezioni Coat. This item doesn't cost a fortune, but definitely deserves a place in your wardrobe. It's also worth checking out this Max Mara Coat. This piece is extremely popular and, just as importantly, not very expensive. Look at this Helmut Lang Coat too! Great value for your money.