Amazon currently lists FCS – but as Ian said, it's at a very stiff price.
For some time after FCS was discontinued, it was possible to purchase it over the phone from Apple. Although I haven't heard reports of recent purchases, it wouldn't hurt to give a call.
If you're convinced FCPX isn't for you, then you might want to check out Premier Pro, which is similar in design to FCP. Adobe has a 30 day trial and, if it meets your needs, it's possible to get their entire Master Suite via a monthly subscription.
Personally, I like many things about FCPX and use it increasingly, though I'm still much more comfortable with FCP7.
Whatever you do, good luck.
I have FCP7 versions but when I try to install on Mountain Lion it does not let me. I than uninstalled FCX on my new 27" iMac. Now it say cannot install on PowerPC... What do I do?
I have a retina MacBook Pro that I did a migration from snow leopard machine and kept FCP7 on it and it runs fine.