Or, you could just pay the fair market price for it, as intended.
Some time ago, I bought a game (don't recall which, maybe Black) the day it came out. EB said that I could buy it used for $15 under the list price. That is very odd - to be able to have the game compete with itself on the release date. In the US...it could be said to violate fair trade. The "used" game's profit goes to EB, not the manufacturer.
In fact, the resale of any video game does not benefit the people that made it. It does benefit the retailer, however...and users to a great extent.
Umm...modding is not an ethical practice, but I am not responding to argue that point. I do not have a lot of money, either...I buy used games a lot...but, I try to restrict it to games that are very old - 3 years or more. After the first year, games prices plummet.
Anyway...there are many websites you can visit for mods - hardware and software.
http://mod-chip.com