Where did you sink the most cash into?

I'm not interested in how much anyone  spent, but I'm curious what the single most costly item in your system is- ie, amplifier, CD player, etc.

I will go first- in my present set up, it's speakers. 

But I can't live without my ancient Zerostat (the red one) which was probably 1/3 if what they retail for now. My most enduring audio purchase!