This isn't exactly DIY, but we got our first estimate for spray foam insulation in our attic, and are looking to compare the price. For a townhouse attic, 20x20x2, 6 inch cellulose foam of the underside of the roof and the two walls shared with neighbors, we had an estimate of $2,200. Does that seem reasonable? Company gets good reviews on Angie's List and we got personal recommendation from trusted source. Will try to get couple more estimates. Thanks!