I have a pretty stupid reason for not being rich at the moment. Basically, I got excommunicated and had the Pope call a Crusade to Rome (my capital). Practically every Christian faction joined the Crusade against me, and my Apline forts were soon under serious assault. With a bit of luck I found the Pope hiding on an island somewhere, and had to offer him my whole treasury plus most of my turnly income (around 15,000F) for the next 20 turns. I only need to pay this tribute for about 7 more turns thankfully.

The reason I never built many stables before was that they are so expensive and didn't appear to do much more than add a couple of units to the Feudal Knights recruitment pool. Still, now I know about the Stradiots I'll get building those Stables, thanks for the advice everyone.