Apple cider vinegar can be diluted half-and-half with water for external application, and, when stronger measures are needed, it can be used full-strength.
1 Just the stone for a flagstone patio can cost $3 -$5 a square foot or more, depending on location and the type and quality of stone, or about $600 -$1,000 for an average patio up to 10'x20,' and $1,200 -$2,000 for a larger 20'x20' area.
Tile costs $5.00 to $9.00 per square foot. Flagstone or Slate: are great products, but they are hot to walk on and create elevation differences, (tripping hazards), where the area stops and starts and the concrete continues. This problem is apparent in the example picture on page 2.