Finding private gold buyers is something that many botters struggle with and end up having to sell their gold to Chinese companies for 1/4 of the value and risk getting a ban due to trading with a crummy ip address.
Sure you can post on multiple forums but a lot of the time, getting enough buyers this way is very slow.
This is what you do.
1. Go to your AH
2. Go to trade goods and sort by price
3. Check if there are any items selling for ridiculous amounts e.g. 5x linen cloth for 4k each
4. Add the seller to friends/whisper them/write in game mail
5. Be polite and say something like I will give you half the price
Other common items are bandages/cheap enchant mats/ whatever/
and there you have it!
May be useful to some. I know that I was struggling to find buyers up until just yesterday but I have found a few now.