Costs for Mathnasium vary by program and student's school level. Programs for first through eighth grade students cost $35 an hour for a three-month, six-month or nine-month program. Programs for seventh-ninth grade can cost from $44-$52 per hour.osts for Mathnasium vary by program and student's school level. Programs for first through eighth grade students cost $35 an hour for a three-month, six-month or nine-month program. Programs for seventh-ninth grade can cost from $44-$52 per hour.