In South Louisiana it's Dandelion season and this recipe will not only kill Dandelions but is non-toxic to pets and humans.

Here's what you'll need:

1/2 gallon of Apple Cider Vinegar
1/4 c table salt
1/2 tsp Dawn liquid dish soap

Directions:

Mix ingredients in a spray bottle.
Spray weeds thoroughly.

How it works:

The Dawn dish washing soap strips the weed of it's protective oils so that the vinegar can work.

Cost:

You pay under $7.00 for a 1/2 gallon and this will work better than Round Up.  This solution will also work after the 1st application.