Online retailers

I find myself using Sprue Brothers more and more.

Sprue Brothers has also been a reliable source for me.

Scalehobbiest, price, selection, and have most everything. Only place I know where you can get the Lg bottles of Tamiya paints for $2.39

I have success with Tower.

http://cs.finescale.com/fsm/general_discussion/f/9/t/164696.aspx?sort=ASC&pi240=1

I enjoy the Squadron flyers, and have had good results ordering from them.  

I have also gotten good results from Tower Hobbies and Roll Models.

I have had really good service from Scalehobbyist. Their site is hands down the best in my opinion. It is very easy to apply filters and find exactly what you are looking for. Their packaging is first rate. I have never had anything arrive damaged.

Roger

If you have the patience to wait for what you need at the right price, Ebay is hard to beat, but I guess they're not retailers in the true sense.

I use Free Time Hobbies,because their service is great.  Squadron has some good deals from time to time as well , assuming that you are in the USA.