Gardening and Horticulture - 20% vinegar

Does anyone know a source near West Palm Beach, FL (or a national chain) that carries 20% vinegar? Diluted by half it works great on weeds in my gravel driveway (at least as well as Roundup), but ordered on the internet it costs more than Roundup.

Vinegar kills weeds and can actually kill it faster than the chemical treatment. But the thing is, it does not last as long. it does not apparently stay concentrated at the root level as long, or something. A lot of experience talking here, as I have done both applications (vinegar vs. Round-up-like products that are highly concentrated), over the same areas. Many, many, many gallons of straight undiluted vinegar used in garden sprayer. And then the concentrated chemical, diluted to recommended strength, in pump-up garden sprayer. Bought vinegar because it was cheap. But found that buying the chemical on sale, and comparing it's value, with how long it lasted, made my decision for me. Apples to apples.

If you live out in the desert and it never rains to flush away the vinegar, then a person could rethink this. But with rains washing away the application, the chemical holds up to that better, which has been very obvious in my applications.

Thanks for the advice but it works great on my driveway.

I'm just looking for a place to buy it locally.