I am sorry to hear that's the case. I have a machine running 10.6.8 and iWork: I don't know if it's the latest version, but I think Apple should still be supporting Snow Leopard. Anyways. Found this "hidden" but official download of Apple's iWork Trial: you can't download it anymore from the website, as it tells you the trial isn't available any more and tries to push you to the App Store. This is the link to the dmg:
As far as I know that download runs in Snow Leopard. After you install it it will give you the option to Try for 30 days or to Register with a serial number. You should see a link to Buy a serial number below the serial text-box, as in the picture below:
Go ahead and click that link. I didn't buy it online using this method back in the days, and I know not exactly where it takes you, but I'm guessing it should take to to some site where you can purchase a serial number with your credit card.
In case this link is useless for some reason (perhaps it is takes you to some website telling you to buy it on the MAS), I suggest calling Apple directly, or driving by an Apple Retail Store someday (or a retail store selling Apple Products) as they occasionally are left with spare boxed copies of software (I have seen a few iWork boxes still on my local Office Max).