If you're a thrifty shopper, your best bet is this Blazer. It's a popular item, while not very pricey. Another strong contender for your wardrobe is this Lafayette 148 New York Double Breasted Blazer. While the price of this item is competitive, it will certainly attract a lot of attention. You might also want to consider this Nicholas Vest. The price is very reasonable, but the effect on your wardrobe will be pretty fantastic.
If you can afford to spend a little more, why not check out this Helmut Lang Jacket. While the price is very reasonable, this product is an easy wardrobe update. It's also worth looking at this Theory Blazer. This piece is ultra popular and, just as importantly, not too pricey. And do check out this Set Sleeveless Blazer! It's a very popular item and good value for money.