Decided after doing two batches with-out a chiller, I needed one. I never understood the need for these gigantic diameter mile long chillers so I went with my hunch and built one with 25' of 1/4" OD (yes OD) copper tubing. Made a 5.5 gallon BIAB today with a full volume boil (about 6.5 gallons post boil) and was able to cool it in 17 minutes to 68F by mixing with a spoon or 'bouncing' (lacking a better term) the chiller up and down. Grand total with the copper tubing, rubber tubing, fittings to adapt to a hose, 50' of garden hose, and hose clamps; $22.
One thing I noticed, if I let the chiller sit still for more then 15 seconds when it was in the low 100's, the discharge water would get cold, if you kept it mixed by any method, it pulled the heat out much faster.