i think it is vary from $25 to $80.standard 3tab shingle is 36" long.
ruffly 5000LBS at 250 a square for 3tab shingles can be a little less or more depending on maker of shingles
30 by 40 = 1200 sq.ft. divide by 10 = 12 square 3tab and arch shingles are 3 bundle per square 12 sq. x 3 bundles = 36 bundles 3tab = 26 shingle per bundle arch = 22 shingle per bundle 36 bundle x 26 = 936 3tab shingles 36 bundle x 22 = 792 arch shingles =)