I wouldn't worry about being able to afford riding every round because there are some maps you will not want to be on a horse.
Even then, a courser does put a damper on how much stuff you can upkeep with it. For instance, with a courser, heavy lance, sarranid cavalry sword, heather shield (the brown one, like that copycat Gorath uses), haubergeon, flat topped helmet, mail chausses and mittens I make small, but really small, amounts of money over quite a long time period (to iron out randomness). I do use a horse on almost all maps except the town clusterfuck ones where it doesn't make any sense, however. With a rouncey you can be a lot more liberal with your gear since you have 10K extra available to equip yourself.