Save money by not buying any of your equipment off of AH.  Especially at the lower lvl's, its not worth it because it will be obsolete within several lvls anyways.  Higher lvls it is not as big of a deal.

And limit the amount of money you spend on other supplies such as potions or other components needed to use abilities.  The less money you spend on this the more money you have to spend on something else, like your horse.  I know that dumbing it down, but its an overlooked principle of money saving.

Finally, solo quest little as possible.  This will mean you quest faster, and you will die less, saving yourself repair bills.  Like the opening thread stated, every copper counts.