There is only one way that I can think of that is safe. The chocolate bar method. I'll explain to you just incase you don't know what it is.
Requirements: 3k on the level 3.
1. Have both the level 3 and the account with the 100mil on at the same time.
2. Go to Wyndin's shop in Port sarim with both accounts, south of Betty's rune shop.
3. The level 3 buys a full invetory of chocolate bars, costing 560gp.
4. The account with 100mil trades the level 3 and buys them for wealth value, being 2970gp.
5. The account with the 100mil then sells back to Wyndin.
Repeat steps 3-5. Obviosuly this would take ages and ages and ages. But, there aren't a lot of ways for a level 3.
I hope this helps you,
~Sledge