How to blow in more attic insulation yourself - I have tried this and it's very easy = just get very long - extra long cord/hose to reach into the space from downstairs/outside so you don't have a mess in your house! Can add inches of insulation in one afternoon. Rent machine at Loews or Home Depot for $50 per day.
Home insulation products, including batts, rolls, blow-in fibers, rigid boards, expanding spray, and pour-in-place insulation, can qualify for a tax credit of 10% of the cost, up to $500, if you completed the installation in 2016.
EcoFill™ - EcoFill Wx is an unbounded glass wool blowing insulation with post-consumer recycled content. Designed for weatherizing and retrofitting existing houses, the product is used to dense-pack sidewalls using the drill-and-fill technique common in retrofitting homes or in-home weatherization activities. R-values range from 15 to 23.
Old house BALLOON FRAMING insulation information... in summary "There is no reasonable payback to blowing insulation, foam or dense pack into the plastered sidewalls of your old or historic house. This practice has truly been the ruination of many of our historic central city homes."