I don't know if this is normal, but sapphire mines are the most expensive out of everything. From 500-600 diamond it costs me ~120 nonilion, and from 400-500 sapphire it costs me ~700 nonilion
here is a mini guide: take a piece from the bed(the cover), a piece of glass, flush the toilet and get the nut, then get the button which is nears lewis finger, use the glass on the piece from the cover of the bed, talk with hatter, go to that dead monster named lewis, cut him with the knife, cut the stomach in the soft part, kill the worm with it and then wait.. when ur back in the room go to the door and u can enter it... then go in the room and click on computer.. password is march.. write Unlock march.. then go in right and get the pictures from safe, then u go to that picture and make it to have a chicken head, a heart and a hand to drop a coin.. then enter on door, click the button and that is all.. good luck :)
alex for me works perfectly:|.the ideea is that if u repeat the same lv and lets say u do it always A u won't get always grade points, just the first time u did it, and u can get from same stage just if u do it AA or more