You might even click on our advertisers and see what they have to offer. I have heard they are fair and competitive. And it a great way to say thanks to them for sponsoring Trainboard.com.
Online Trains in Lakewood Wn. is a good HO shop. Whistle Stop Trains in Portland Oregon and Branchline Hobbies in Longview Texas.
I've always had good luck with Dallas Model Works too. Great service!! http://www.dallasmodelworks.com
Like Darren said, http://www.caboosehobbies.com not only my Local hobby shop, but also my Internet spot as well. Great prices, service and selection second to none.