what is your pick for a on-line retailer? which ones should be avoided? thanks
I like www.spruebrothers.com
I think spruebrothers are probably fastest,and GM is a few dolloars cheaper here and there,and they have a superior search engine.
I second SprueBros. I’ve also had very good luck with www.scalehobbyist.com. Good company to order from, well maintained real time inventory web site, prompt shipping.
Bob
Depends on what you want (era, country); I pick whats on sale 
Sprue Brothers has some in their “Super Savers” category, Free Time hobbies has good prices, and GreatModels have occasional good sales. Lucky Model cant be beat for trumpeter, bronco and most AFV kits (if you like subs), but takes months to get to you. Finally, depends if/what PE you want to use. LuckYModels has the best prices for Lion Roar/Flyhawks. WEM/GMM I get frmo free time hobbies.
I have had good luck with Squadron, including making things right when an order got screwed up.
Also Roll Models.