I'm afraid you're going to have to buy items from shops and then break them down from there. The items should be about worth the same in components as credits. Find the shops with the best values (Geeda on Nar Shaddaa or the alien outside Kunda on Dantooine) Repair skill of 20 is the maximum breakdown skill level you can get as well. It has to be the PC character with 20 repair skill, not the one using the workbench.
Hope this helps.