Finding the right type of barrel can be the biggest challenge in putting together your rain barrel, and is often the reason why people purchase rain barrel kits. Food-grade barrels have a special hard plastic that prevents the barrel from warping as it fills with water. If you're on a tight budget and are persistent, you'll find a food-grade barrel for little money.
Search online for rain barrel workshops in your area. They may be held through universities or community colleges, environmental non-profits, small organic farms or adult education centers. Workshops will teach you how to build a rain barrel and provide the food barrel as part of the workshop fee.
Call your local environmental non-profits to see if they have a list of commercial suppliers that use food-grade barrels. If they don't, use the Internet to research companies in your area. Some environmental non-profits sell rain barrel equipment, including barrels.
Contact the companies on your list. Ask if they have 55-gallon barrels, if the barrels have lids and whether you could purchase or have the barrel. Some companies are happy to get rid of them.
Prepare another list of food wholesalers and food distributors in your area and contact them if you're still looking for a barrel.
Contact your town's recycling and trash department and inquire about food-grade barrels. If your town's officials do not allow food-grade barrel recycling, they might have information about obtaining these barrels at a low cost.