Just for clarification of K4's post the ps1 exploit was called the "Independence Exploit"
and that is of course the cheapest way to go ... on the road to Free Mcboot.
Basically all your doing is looking for a way to install Free McBoot on your memory card
so the best option would be to find someone who already has a way to run elf files on there ps2 and get them to load it onto your memory card for you.
now the other options are a bit more complicated.
You could buy a cheat disk (code Breaker, Action Replay, Game Shark) although certain versions are required in order to boot Free McBoot directly