Once I got to about 30K worth of gold saved up I had no problems with upkeep. This was before I had a good, solid equipment load out for my lancer cav character.
I now sit comfortably utop a pile of 100k gold, which, despite my occasional plate armor/armored horse adventures remains constant. This is the most expensive class in the game--cavalry, and I ride a courser constantly, which isn't cheap.
As the above posters have said, get a nice, 'average' priced set of equipment and play until you get a nice reserve saved up. Then play in your expensive shit (occasionally). What build are you, and what equipment do you use?