Depending on the size of your insulation project, there are basically two places to get spray foam insulation for your home or commercial building. Size is a crucial factor because most projects are just too large, too technically difficult or have complicating factors that make spraying foam inadvisable for the average person or handyman.
The first place to buy spray foam is a home improvement store. You can buy small cans of spray foam for touch up projects. Insulating around windows and doors is a good-size project for do-it-yourselfers. You can easily fill in gaps that are leaking air and save yourself a few energy dollars and the hourly cost of a pro that can also tackle this project for you.
The next step up will require that you buy drums of spray foam materials. There are smaller canisters that you can buy from home improvement stores. The caution here is that you have to take what the store has in stock, which may or may not be the optimal product for your application. Spray foam comes in many formulations of closed and open cell foam, and the right one for you may not be on the shelf. Further, few big box home improvement stores have the requisite knowledge base within their staff to advise you on proper selection, application and best practices. Those canisters are best used by professionals who need that exact type of foam for a small job.
The widest selection of spray foam will come from a professional installer who has access to the products of the dozen or so manufacturers that have foam products. They know the best sources for particular formulations of foam that are ideally suited to your project. These specific formulas are available in large drums and require professional spraying equipment and a well-trained team to install them properly. They will also know the latest innovative products that will maximize energy efficiency and with the latest in eco-friendly characteristics. If you are investing in spray foam, you will probably want the most current formulations that will meet your project requirements the best.