The only way i know to transfer gold is either transferring you character cross realm (25$ cost to do so), or finding someone on the realm you want the gold transferred to and get them to trade the same amount of gold by you giving them that amount on your realm. The issue with that is there aren't many people wanting to playing on another server.
Be warry though, if you do transfer realms remember,
Characters carrying too much gold are not eligible for transfer, as follows:
Level 10-30: 300 gold limit
Level 31-50: 1000 gold limit
Level 51-70: 5000 gold limit
Level 71-80: 20000 gold limit
Level 81+: 50000 gold limit
If you willing to transfer to Sisters of Elune i can pay you 5kgold for 5kgold on your realm.