Where to buy reef plugs?

[kingfisher62]

I was thinking of buying some plugs to keep on hand. What is the best type to use? Ceramic Vs Concrete or at least they look like concrete ?
Where do you get yours?

 

[shifty51008]

http://www.bostonaquafarms.com/?q=ceramiplug

 

[csharps42]

reef plugs

reef plugs

Seems like I just saw some, they may have been on ebay, or maybe bulk reef supply