I usually buy all my ICs, transistors, diodes, etc from Mouser. What they don't have I get from UTSource. So far, I haven't received any obviously bad parts. I was skeptical at first because their (UTSource) prices seem fairly normal for "hard to find" parts when compared to specialty guitar pedal shops that charge $3 for a single diode or whatever. Take this recommendation with a grain of salt since I'm a newbie and I haven't actually tested any of these parts -- but all of the pedals I've built with them sound good to me.