You can buy them off the web as legal back ups,
I used to buy back up Xbox games from this web site.
http://www.cd-backupz.co.uk.
They are very reliable, and provide a good service
The only problem is they only sell Xbox & PC games. You can find web sites that sell legal back ups by searching for PS2 back ups.
As buying copies is illegal, you can only buy back ups which is perfectly legal as long as you own the original. Normally web sites expect you to tick a box saying you own the original.
It�s unlikely that people buying from these sites have the originals, but this does create a legal loop hole which is used for web sites to operate. The site above has been around for a few years now. It may be worth asking if they sell or can refer you to a back up supplier for the PS2.
But remember that any buying of back ups is a bit dodgy (or copies), so be careful!