I live in Florida and have fought with warm tap water for almost 10 years in this hobby. I went through all the ideas for pre-chillers and such.
Pre-chillers in ice water while not efficient, can be used fairly effectively with a plate chiller after the wort has been recirculated down below 100 with tap water in the kettle, and ice then added to the pre-chiller bath. Before the wort is down near 100 it's a waste. As long as your tap water has at least a 15-20 degree differential it is effective, so adding ice too soon only wastes the ice and doesn't really improve chilling much.
My current method is to chill and recirculate to near 100 with tap water, then swap the tap water hose for a submersible pump in ice water. Crazy fast chilling.
I also have two Blichmann therminators that can be used inline with the first on tap water and the last on the ice water pump. That can allow me to pump 10+ gallons of hot wort directly into a fermenter and get a finished temp in the fermenter below 60f as needed.
I make the ice in the freezer during the week so I don't need to buy it. I probably use about 15lbs of ice for a 10 gallon batch, but I'll have to weigh it some day to be exact.
I haven't yet seen a glycol rig that I can afford that had the BTUs to do the same. The pump was about $40 (get at least 1/4hp not a little "pond pump"). The rest is garden hose and quick connects from the hardware store.