First, I'll clarify where I stand: I had a 2009 MacBook that came with iLife '09. In 2013 I upgraded to a refurbished
2010 MacBook Pro with OS X 10.6.4 that, without my realizing it, came with iLife '11, so I thought my iPhoto 9.x was simply an update of my iPhoto 8.x when it was, in fact, a whole new beast. (My MBP's original release date preceded iLife '11's release by around 6 months, but Apple gave me the then current version in 2013.)
As I said earlier, I didn't realize what had happened until dk posted.
Getting back to you, though, you can certainly install iPhoto 9, but (Edit: I believe) you'll have to buy the entire iPhoto '11 suite of apps.
It seems like it ought to be somewhere in the App Store, but I'm not familiar enough with the store's workings to find it if it is.
It is, however, available on eBay…perhaps elsewhere.
Update: I just found
this Apple.com page that says "
Product No Longer Available", so I guess you're stuck with eBay et al.