Have had no problems with training costs but I never feel like I have too much money either, a good balance. My lvl 50 bounty hunter has everything trained plus crew skills at 400/400/400, lvl 3 speeder, 3 ship bays, max inventory, and had almost 250k left over after reaching 50 and training all the skills (many of which were upgrades and only 11k each). Cant say how money is after that as Ilum was frustrating and I wanted to enjoy the other class storylines. I also have a bunch of lvl 17-20, mostly they have spent some money on crew skills as necessary, have all skills trained to their level, and have 15-20k in the bank with one upgrade to inventory bought. I don't bother with the market (either buying or selling), kill everything in my path to quests and sell the loot, no flashpoints, no PvP, and I fly the occasional space mission.