After having several sets of photos taken for passports, at various locations, I was advised to have them taken at Jade Studio. I was told "they never get them wrong" by the Post Office, who has to process the passports. This was confirmed by the owner. He told me he has never had anyone come back to have photos redone. He took a good photo the first time around, and it was perfect according to the Post Office.
Approximate cost: $20 for 2 sets. Cheaper than anyone else quoted.