Below is a collection of images taken from various vendors that offer items for your Stronghold. Some items are acquired by Credits, and others by Universal Prefabs or Cartel Market Certificates. Each denotes which currency is necessary for purchase in the upper right side of the image.
Each of these vendors can be found on Carrick Station (Republic Fleet) in the Stronghold section located on the inside outer ring. Click on the images for a larger view.
Universal Prefabs are either player made, and/or purchased from the GTN from other players at the current market value. Cartel Market Certificates on the other hand, are bound items not offered anywhere in the game except as a random drop from Cartel Market packs purchased from the Cartel Market, or from other players on the GTN. You can however periodically find the items purchased by other players and offered on the GTN.
For a great reference on other places to acquire items for your Stronghold, visit the Tor Decorating Vendors and NPCs page.
SWtOR - Cantina Cartel 