I use a couple of two-quart juice jugs to do this. I haven't had any infection problems in about a half-dozen batches. My sink is too shallow for my kettle to cool quickly, so this was the next step. Maybe I will step up to a chiller soon.
I selected the rectangular ones on the theory that they will have a higher surface-area to volume ratio and thus cool more efficiently. Also, they are a little more study than the standard two-liter soda bottles. Make sure your jugs will fit inside your kettle with the lid on.
I cleaned label glue off with Goof-off (basically mineral spirits) and let them air in the sun for a couple of days.
Leave room for ice expansion when filling, otherwise they will split or you will have to remove ice from the mouth to seal them before using.
Just before putting the kettle in the ice-bath, I get these out of the freezer and soak in my sanitizer in the other sink for a few minutes. Turn them a couple of times to get all sides sanitized. Then my kettle goes in the ice bath in the sink, and one or two jugs goes in the kettle.
I think few bugs can survive going from the freezer, through the sanitizer, and then being plopped into 190 degree wort. At least that is my theory.
Have something handy to put the jug in when you take them from the kettle so you don't drip wort on SWMBO's kitchen floor. Then empty and clean them really well before storing for the next batch.
One problem I have is that they try to float in the kettle. I am contemplating adding some ball bearings or something to the jugs before filling to help steady them on the bottom of the kettle.
Chris