Before you use a cooler bin for sous-vide, make sure you're aware of a few necessary precautions.
For thin cuts of tender steaks (1" or less NY Strip or Filet Mignon) or other tender meats (i.e. fish) that will safely cook in under two hours, the cooler bin can be a safe and inexpensive alternative.
But b sure to seal the cuts individually and allow enough room for water to circulate around each cut, or else risk dangerous temperature variations in the bath since there is no active heater or circulator.
Thicker cuts of meat require long term cooking. Famous sous-vide expert Douglas Baldwin notes that if you double the thickness of a cut, you should quadruple the time to ensure cooking safety. Since cooler bins lose 1-2°F temperature per hour, they may not hold the desired temperature long enough to properly cook a really thick cut of meat.
Cooler bin limitations affect other areas of sous vide cooking. You can not do long-term tenderization of meat at a specific temperature such as required for 72 hour sous vide short ribs.
Finally, food that is not sealed in food grade plastic may not be safe depending on the container you use. For example, cooking "cooler Corn" in cheap plastic beer coolers can leach toxic chemicals into your food. The websites out there promoting the awesomeness of "cooler Corn" neglect to mention that you can only make this technique safe if you have a large "food grade" styrofoam container (i.e. the same stuff that is manufactured to hold boiling water for tea or very hot coffee).
I'd advise against using a cheap plastic cooler without sealing your food "sous-vide" or you will risk contaimination.