Two players on Xbox Live, and potentially system link, are required. Go to Chapter 5-3 and begin the fight with Wesker. On the way there are two or three Reapers, a necklace, and some Lickers-- all of which result in about 15,000 to 20,000 gold. Once in the fight with Wesker, have him throw a player through the door, then run up stairs and have both players shove the casket lid off to get another gem. The player that will receive the gold must not host the game or else the host will only receive some money. Defeat Wesker within his seven minutes (Magnums recommended) and he will drop the Heart of Africa, which is worth 10,000 gold alone. Once he drops it, you can pick it up during the fight with Jill. After picking it up, have the second player leave the game and save their current equipment. Then, have the second player rejoin and the host restart from the last checkpoint. The checkpoint will be the start of Jill's fight, meaning that one can pick the gem up again. Repeat this as many times as desired.
When you get a rotten egg, let a co-op partner join you. Give it to them, then start a chapter. After the "Saving" message appears at the top left corner, die. Then, have them enter the inventory menu and give the rotten egg back to the host. The partner that joined you should go to the Xbox Dashboard. Invite him or her again. Both you and your partner will have the rotten egg. Do this multiple times to multiply the eggs. When you have about 100 rotten eggs, give all of them to your co-op partner. Repeat the method until the host ends up with 200 rotten eggs. The host can sell all of them for around 1,200,000 gold. After that, start a chapter so the "Saving" message appears again, then quit the game and let your co-op partner host the game. Now that your co-op partner is the host, he or she must give all those eggs to you. Start a chapter, die again, and give all those eggs to the host (your first co-op partner). You must go to the Xbox Dashboard this time. The host can now sell all of the eggs so both of you get 1,200,000 gold pieces. You will still have the rotten eggs since you went to the Xbox Dashboard. Buy all the weapons and most of the upgrades. If you need more money, repeat the glitch.