Direct answer
Most Cincinnati homeowners spend $1.50–$2.50 per board foot for closed-cell, $0.50–$1.20 for open-cell. A typical 1,500 sqft attic runs $4,500–$8,500 closed-cell or $2,000–$3,500 open-cell. Free in-home estimates.
More detail
Pricing varies with foam type, application thickness, accessibility, and removal of existing insulation. Federal tax credits up to $1,200/year (Section 25C) are available through 2032 for qualifying upgrades.