Are these cables a good buy?

I am a real fan of buying used items in general, and I understand that in audio in particular this is a great way to maximize vale. However, I see that Audio Advisor has a big sale on MIT speaker cables: MH-750 Series II Bi-Wire (12-feet) for $575 and Terminator 2 bi-wire (12-feet) for $225. Are these deals worth pursuing? What is the relative value differential between the cables? I am just getting into this habit and want a decent set of speaker cables for $500 or less that are versatile enough that I can use them with different amps and speakers in the future.

Thanks, Matt