C Class Example: Brave Cookie's Third Skull Button
Picture
Level                     Coins            Crystals
  0:                            N/A                  N/A
+1:                            2,800                  2
+2:                            4,200                  3
+3:                            5,600                  4
+4:                            7,000                  5
+5:                            8,400                  6
+6:                            9,800                  7
+7:                          11,200                  8
+8:                          12,600                  9
+9:                          14,000                10
_______________________________________________
Total:                      75,600                54

B Class Example: Cozy Yarn's Knitting Needles
Picture
Level                     Coins            Crystals
  0:                            N/A                  N/A
+1:                            6,600                  4
+2:                            8,400                  6
+3:                          11,200                  8
+4:                          12,500                10
+5:                          14,600                12
+6:                          16,700                14
+7:                          17,200                16
+8:                          18,600                18
+9:                          20,000                20
_______________________________________________
Total:                    125,800              108

ตามนี้ครับ Credit web: http://cookierunline.weebly.com/upgrading-treasures.html นะครับ