Don't buy it! It's really easy to make, just follow my homemade chipotle barbecue sauce recipe and you can have your own smoky BBQ sauce in under 30 minutes.
The base ingredient chipotle, (pronounced chee-pot-ley) is a smoked jalapeño that you can either buy or smoke yourself from the red jalapeño pepper.
If smoking yourself you can use green jalapeños but I don't think the end result is as sweet and it's not really authentic because of how the chipotle is produced.
Like many peppers, the jalapeño is first green and then ripens to a deep red color and it's at this stage that most of them are harvested and sold. The chipotle is prepared from any jalapeños that remain on the plant at the end of the season ie. those that are withered and dried.
You then smoke them to produce the end product, an ingredient that adds heat but also its own distinctive earthy, smoky flavors unique to a chipotle barbecue sauce.
The most common way to buy chipotles is in adobo sauce which essentially is a mix of spices, vinegar, tomato sauce (and sometimes other chilies) that's presented in a can. You can use the canned variety in this recipe, no worries.
Heat the oil gently in a sauce pan, throw in the onions and the minced garlic and fry gently until the onions turn clear (about 5 minutes).
Now add the rest of the ingredients and simmer, bring the mixture to the boil and simmer. How long do you simmer? Well, you'll know when the sauce is ready because it will start to thicken (and probably make a mess of the stove top at the same time).