CrossRoads:
I bought a bunch recently myself. They have pretty good prices.
I don't know who in the forum identified them as a source.
Great price on MAX7219s also.
After Tayada's DC jacks for a while, I wouldn't recommend these 
Great price but terrible quality. Every one I used failed quickly, slightest touch to cable and my clock looses power (and I tried several different DC wall adapters)...
I since switched to Switchcraft 722A and they are amazing! Plug goes in smooth and stays in, stays connected but also easy to remove. Looks like they are silver plated too. Expensive tho ($2.64 for 10 on DigiKey), but you definitely get what you pay for 
If I could find these for a $1 I'd bee extremely happy!