If you're on a thrifty mission, your best bet is this Barbara Bui Trenchcoat. It's a popular piece, while not very costly. Another strong contender for your wardrobe is this Calvin Klein Trench. While the price of this product is competitive, it will definitely attract a lot of attention. You might also want to consider this Mango Trenchcoat. The price is very reasonable, but the effect on your wardrobe will be pretty fantastic.
If you want to splurge on a luxury piece, then what you're looking for is this Josie Natori Trench. It's more expensive but worth your money. While you're at it, also have a look at this Ports 1961 Trenchcoat. Yes, this item is expensive, but it does not mean it's not worth it. And one more item you might be interested in is this Burberry Trench Coat. 'Cause you deserve nothing but all the finer things!