You can transfer a fair amount of gold with a toon, if the toon is higher level.
As in level 80 on current server to new server.. I think its 50,000g or so.

If your server is a pvp one, that you cannot have both alliance and horde toons.
If its a PvE realm then this is super easy, since you can have toons on both factions.

If it is PvP, consider a new account anyway, as in going from 5 accounts owned to 6 accounts owned.
You'll still only have 5 accounts active at once.
The sixth account will cost you the price of a battlechest plus WotLK and 25 for the server transfer.
Still 50k gold or thereabouts on the new servers horde side will dramatically help you.

The easy way to transfer is to put something up for 50k gold on the neutral AH.
Horde toon on account 1 lists, alliance toon on account 2 purchases.
You lose 15% of the gold amount as AH fee's which sucks.

A better way will be to purchase enchanting mats, because they sell very well and cost nothing to list.
Any high end item, from Ulduar BoE's to crafted epics will work as well.
The alliance toon purchases these, and will eventually list them on the neutral AH.
You'll want to have your own toons in Booty Bay, Gadgetzan and Everlook so you're sure no one else can buy your stuff.
List it cheap on the alliance toon.
With another account purchase it with the horde toon.
Now have the horde toon go and list it on the horde auction house.
Gold has been transfered.

Being able to semi-twink a toon/team helps them level a bit faster.
Buying all of their spells, at least the ones you'll use helps too.
It's an option to consider.