I found this HP document via an other web site: HP Printer: Photo page yield details
http://h10060.www1.hp.com/pageyield/us/en/...9180/photo.htmlIf the URL is chopped, search on: B9180 Photo page yield details
Based upon the numbers on that page, Light Gray is the killer
HP B9180 Printer cost each 1/3 off list cost per 11x17 11x17 pages 4x6 pages
HP 38 Photo Black Pigment Ink Cartridge $28.99 $0.1602 180.96 1410
HP 38 Magenta Pigment Ink Cartridge $28.99 $0.0452 641.71 5000
HP 38 Cyan Pigment Ink Cartridge $28.99 $0.0481 603.21 4700
HP 38 Yellow Pigment Ink Cartridge $28.99 $0.2689 107.81 840
HP 38 Light Magenta Pigment Ink Cartridge $28.99 $0.4107 70.59 550
HP 38 Light Cyan Pigment Ink Cartridge $28.99 $0.1779 162.99 1270
HP 38 Light Gray Pigment Ink Cartridge $28.99 $0.7059 41.07 320
$1.8168 est total cost of ink for 11x17
$1.3990 est total cost of ink per sq ft
$15.0602 est total cost of ink per sq m
Supplemental cartridges
HP 38 Matte Black Pigment Ink Cartridge $28.99 $0.0753 385.03 3000