Picture, Poster and Patches Sources

[Offsite Links] does NOT sell insignia, posters or pictures. 
A search of the internet will reveal a number of dealers. 
Here are a few links to check.  A hearty thanks to those who have graciouly donated scans to this site.

Patches/Insignia - LJ Militaria sells vintage original patches and collectible military gear. - USMC aviation insignia galore.
Military-Graphics - Jim, USN retired, turns any patch or military emblem into a vinyl decal at a reasonable price - Chief McGrogan carries an outstanding stock of small unit insignia and brown water Navy items.  - USCG retiree with the best selection of Coast Guard items.  Check Rex's reference book on USCG patches.
Barewalls Posters and Prints -A bit of everything. - Affordable reproductions. - Nice originals at a price.

Pictures - DoD information. Get through the pics of back slapping bigwigs giving each other bonuses and you'll find the good material.  - National Archives and Records Administration (NARA).  Patience will yield amazing results.  - Naval Institute picture library has all U.S. Navy ship photos back to 1900 for a fee.
Library of Congress - Hidden treasures for the history buff if you dig.
National Naval Aviation Museum - Buehler Library holds over 500k U.S. naval aviation photos and on request will provide a limited number of digital scans via email.