i use a canon s9000 to print my photos, and am paying an extraordinary amount for ink replacement cartridges. i see non-canon replacement cartridges, advertised as "compatible" to the s9000, online for much less money. i asked an employee where i buy my supplies why they were so much less expensive online, and he replied that he would not trust anything not made by canon. is this true? is there a difference in quality when using non-brand replacements? is there any danger to my printer? thanks in advance for your replies.