I own a spray foam insulation business we started in 1999. I work with the fiberglass guys. You are getting a quote for an r20. I sell (quote) for a fiberglass buddy @ $.50 for a r 30. Your Radiant Barrier Price is high from what I have seen. I have checked many attics with a I.R. thermometer and never see much of a drop with the spray on RB. The plywood backed will lower the surface temp 35 degrees. Foam could be applied @ $1.25 and it works in the summer and the winter. Shop around.
ENVIRO TECH SPRAY FOAM INSULATION