I don't "buy" gold unless I am in an extremely sticky situation, which I rarely have.
Recently I'm venturing into enchanting business which does pay off fairly well.
Actual gold amount I feel broke when i have below 10m, Feel wasteful when i have less than 20m. and feel like i indulged myself when i have less than 30m in my bank.
Wonder how i feel when i get enough char cards to hold more than 40-50m...
Or you can go the check route.
Especially if you see the same person buying 4 items in a row worth 7 mil+ and then next week buy 4 more items with 7 mil+ money.
I figured that this is actually possible under a few situations. Some people buy things cheap and resell for a high profit. The other is to take risks with enchant and sell the end-products which are much expensive compared to cost price. Take for example Viper scroll which is worth about 500k and Jackal scroll about 200k. End product is worth at least 7-8 million. You are making big money there. Makes enchant training so totally worth it.
I have rather good luck with enchants, except for enchants like habit and little raccoon which I will avoid as much as I can due to negative experiences with them.