I started out with 700g, and am now sitting at 4544g, all in 3 hours of running around IF.
THIS DEPENDS ON YOUR SERVER'S ECONOMY HEAVILY!
Step 1. Buy Undeath Deck or make your own. (Sells for 600g on my server.)
Step 2. Convert Deck to card. (Sells for over 1k)
Step 3. Find someone stupid to buy your card.
The reason I posted this is because it takes advantage of peoples laziness/stupidity.
I have bought 7 decks for 500-700g and the cheapest I have sold the card for is 950g, best sale was 500g + Titansteel Shanker (Turned around and sold for 1500)
The key to making this successful is making sure that you buy out the cheapest card of one number (Example, buy out all the four of undeaths.) so when people check the AH to see if they can make their own deck for cheaper they see that there is one type of card missing, thus being unable to make their own deck, if they're hell bent on making their own deck, sell em one of your cards double what you paid for it.