2:
  COMMAND: 'op:manuaddp {player} echopet.pet.type.blaze'
  NAME: '&eBlaze Pet'
  KEEP-OPEN: true
  LORE:
    - '&c$580'
    - '&aSummon a blaze pet!
  ID: 369
  PRICE: 580
  POSITION-X: 2
  POSITION-Y: 1

Note: "manuaddp {player} perm node" is the Group Manager command. Change this if you use a different permissions plugin. "op" denotes console, *I think*.

Price is how much you want to charge for it. The price in "LORE" shows the player how much the price is.

ID is display item ID.
Position-X and Position-Y is where it will display in the GUI.