If you're moving your toon for any reason, the first problem you're likely to encounter is the Transfer Gold Cap, a.k.a. the amount of gold you can transfer from your current realm to the realm you're transferring to. The gold cap has been increased in Legion to 250,000 Gold for levels 100 and above. Now, the problem is 250K is nothing, the vast majority is sitting at millions of gold and the problem is you can't transfer more than 250K. Well, with this method you can. Before we look into it, here are the current caps for gold you can transfer.
1. Level 10 - 30 - 300 Gold
2. Level 31 - 50 - 1,000 Gold
3. Level 51 - 70 - 5,000 Gold
4. Level 71 - 80 - 20,000 Gold
5. Level 81 - 99 - 50,000 Gold
6. Level 100+ - 250,000 Gold
How to Transfer Over More Than 250K?
Let's say have 700K and you want to have all the gold transferred over to your new realm. The method's quite easy, craft mounts.You will have them in your inventory and can resell them on the realm you transfer to. Depending on the gold you want to transfer (additionally to the 250K crap) craft as many mounts as needed to transfer over the rest gold.
1. The first method uses Jewelcrafting. Jeweled Onyx Panther is your best bet. If you have Jewelcrafting I'd recommend you to craft the mount. It requires 4 mounts of different color. The most expensive mount component is Orb of Mystery, which costs 20,000 Gold and can be purchased by a goblin walking just outside of the Siege of Orgrimmar raid instance. The rest can be bought in the Auction House. Probably Titansteel is going to be the second expensive mat. You should have no issues crafting the mount under 100,000 Gold. What's best, you can even sell it for more than 130,000 Gold. If you don't have Jewelcrafting ask a friend to craft one for you. If you don't have both, simply buy it off the Auction House on your current realm and resell it on the realm you're transferring to.
2. Sky Golem - the second method makes use of Engineering. The Sky Golem mount is still a really nice commodity. It allows players to gather herbs and nodes without dismounting. And aside of that it looks cool. Crafting costs 4,200 Elementium Ore and 30x Living Steel. Engineers need 30 days to complete the mount, because you'll need 30x Jard's Peculiar Energy Source (BoP), which has a 24 hour cooldown. Nevertheless this is a more time-consuming method and it's advised only if you're patient enough and have Engineering. It can yield you a lot more gold than the Panther on your new realm though. If you again, don't have Engineering or time, buy it off the Auction House and resell it when you're transfer is finished.
We don't want you to lose gold. Make sure to check out mount prices for both realms. I recommend using website such as the Undermine Journal or TSM. Good luck!