Always be on the lookout for people selling materials in trade chat. You can get some really good deals because usually the people advertising in trade are wanting a quick sale. Try to feel them out and get an idea, if they will let you. Maybe you can set up something where they will continue to sell to you. For example, this was the basics of a player I met this morning in trade chat.
Him: /2 WTS 4x Frozen Orb.
I usually buy these out 20g and under and flip to Eternal Fire and sell for 30-35g per. AH had the Orbs at 26g at the time. So instead of offering him an amount...
Me: How much would you take for all 4?
Me: I will give you 75g for all 4.
Score. I just got 4 for less than I usually buy them out. Big deal, right? Now I continued to explore him.
Me: Do have any other good deals?
Him: I have stacks of Borean Leather and 1 Arctic Fur.
Me: How much for your stacks of Borean Leather?
Him: 5g per stack. 50g for the Fur.
5 per stack is super low, these stay over 12-14g per stack, almost always on the AH.
Me: I'll take all your stacks of Borean for 5g each.
So he sold me 9 stacks of Borean for 5g each and tossed in a stack of 18 Borean Leathers as a "bonus" as he called it.
So thinking ahead, I explored it a little further.
Me: So are you a skinner?
Him: Sure am!
Me: Nice, are you going to be selling anymore skins? If so I will continue to pay for 5g per stack, and you can COD them too me anytime, any amount and I will buy same day or next.
Him: Sweet! Sounds good. I'm going to go farm some more right now. I can probably get you 50 or so stacks today and I will Send them to you tonight.
Me: Sounds great.
Him: Added you to friends and will send them tonight. Thank you Very Much!
Me: Thank you too!
Can't wait to see if he becomes a reliable source.
Lesson Learned? Don't just get your good deal and move on. With a little exploration, you just might find even better deals or, better yet, you may find yourself a low priced supplier. Just remember to be courteous, polite, and fair.