Oddly enough we use Allied electronics for most. We originally started using them, because we were ordering electronics and it was easy to combine the order.
We have links for ourselves at the bottom of this
team page if you want to see examples.
http://www.automationdirect.com/ is the source FIRST lists in their "Were To Get More" document on the KOP Website.
Wherever you choose to order from you have to be careful when you order that the item, especially if it's a special one, is in stock, otherwise the lead time is good only for next season...
Ships from Japan are not very quick.