Stephen,
I did my first ~30 gallon water change on Sunday. As far as better P.E. it's hard to tell (already have great P.E.)
I don't know what it cost, I got two buckets from Kingfish and some other misc items and handed over a blank check (hasn't cleared the bank yet) but I think it was right around the $100.00 range for 200 gallons.
One thing that impressed me right from the start is how fast this salt dissolves. It was completely clear 30 minutes after mixing it.