You can certainly buy any variety of sauces from the market and yes, some are quite good but I prefer to make my own for several reasons. First, most store bought sauces have a lot of sugar and artificial ingredients like liquid smoke. I like to control the amount of sugar and use natural ingredients. I also like to vary the flavors like sometimes I make it spicy with extra adobe chiles and sometimes I add roasted garlic to give it richness or soy for an Asian inspired BBQ. Homemade sauces keep for weeks in the refrigerator and can be used over and over again.
Check out the video on my favorite homemade BBQ sauce here.
Here are a few others that I like keeping in the fridge to use all summer.