How do I buy an iphoto calendar with 10.4.11 iMac?

I have Mac OS 10.4.11 I have made a calendar in iphoto (version 6.0.6). I tried to hit the "buy" button but it said that version was too old. I then hit the link to the iphoto store for an update--but it was for iphoto 9.2.1 which requires minimum of Mac OS 10.6.8. My question--could I purchase an older version of i-photo that would operate on Mac OS 10.4.11 that would allow me to purchase the calendar?

Thanks for your input