I said Cloth armor with a medium tier weapon, not Leather Armor with two of em, arrows, and a horse, man. Also it's pretty strange that you're only breaking even on that loadout, seems like it's just bad luck now that I look at the actual max upkeep for it.
HA is an expensive class, definitely not for 1st gen players, but what I'm saying is that it really requires minimal commitment to raise money. Note that I'm saying it's easy to make money- I didn't say it was easy to make it for Horse Archers in full loadout (just like it's not easy for two-handers in full heavy armor to do so), just that it's easy to make it and then send to your cav characters to be eaten up. What you do- what I do- is play with a loadout that makes me money, then send it to characters that require cash money millionaires to play. Pelt Coat + Qstaff will net you a good chunk of change from a single night of play, and is a lot of fun to boot.
Also, I should mention that I personally think upkeep is a really dumb way to balance things, but unless someone comes up with a better way to balance Cav, Ranged, Infantry, Ranged Cav- entirely different classes with vastly different mechanics and playstyles- it's what we have, and it's easy to get around with a small amount of work. If it were up to me there'd be no upkeep, no heirlooms, no gold at all.