wow man you just got burned big time... off hand i know that EB games gives like $70-$80 for a working, slim ps2. BTW, EB is currently running a deal till 11/12 that would have given you an additional 30% in store credit towards the purchase of anything Xbox 360 related.
of course, i myself would have just kept the beautiful piece of hardware to play through the ps2's exceptional library of games and the fact the system is backwards compatabile, being able to play ps1 originals is also a very nice incentive to keep the unit.
oh well, don't let it get you down too much... live and learn.