If I have to buy something off the bottom shelf I'll probably grab a bottle of Ten High, which is Barton whiskey. I find young Beam (which is what Old Crow is too) okay in very small doses. Early Times is another possibility. Old Fitz prime is usually a little more, but a far sight better in my opinion.
The bottom shelf is also where you find most of the American blends, which are a good choice for the value shopper, especially if you're going to mix it with Coke or something. A little bit of whiskey flavor without the bite and burn of a cheap bourbon.
Of course, real "blue collar" consumers actually tend to buy Jack Daniel's and not whatever is cheapest.