Playing with price points...

price-points.rkt

(define repeat
  (λ (times)
    (λ (n)
      (cond
        [(zero? times)
         '()]
        [else
         (cons n ((repeat (sub1 times)) n))]))))

(define inputs
  (apply append
         (map (λ (n decls)
                (map (λ (b)
                       (+ n b))
                     (map (λ (n) (* .1 n)) decls)))
              (range 0 10)
              ((repeat 10) (range 0 10)))))

(define price-points
  (map (λ (x y)
         (vector x y))
       inputs
       (map profit inputs)))

(plot (points price-points)
      #:y-max (+ (apply max (map profit inputs)) 300)
      )