I went from only 1.5m to 50m in 2 days from forging iTCG items and then selling them 
I bought materials for Black Phoenix Shield, Dark Shards, Sirius Cloak, and Zeta Cape
Then i just resold the items and then i get more money than i spend
TIP: Buying items for iTCG is good money if you have a lot of time for the moment. Prices might get lower as time progresses.