One thing to consider. If you are looking for the "true historic perspective". Riding was a significant part of a knights training and is good exercise. There is value in the training beyond just becoming a good, fit rider. I understand it is expensive and time consuming but there are a lot of benefits.
I do ride, with gear, and it is expensive. Why my Vulcan 750 is a persnickety gnarly beast that likes to go it straight lines very very fast, hates corners & cornering, and has practically no real usable range. Would you believe a radiator is $400?! Just for the radiator!
Oh, you meant horses? Yeah I can ride those too. My first MTBI with PCS was from a horse that bucked (cow kicked?) me off when I was 8. Took me 20 years to work up the courage to get back in the saddle. Beyond my issues there is the problem that, at least around here, to truly get good with a horse means having your own land. And that means 10's to 100's of thousands of dollars. For myself I could have learned more, my mom's has had horses again for the last 14 years (she used to be a trainer in the Cuyahoga Valley) & I have a few friends in Cali that have them and they all to SCA Equestrian activities too, but I don't "get" it, so I don't spend the time & energy to get better in the saddle. Heck I don't even get the attraction of riding a motorcycle all the time and I DO ride a motorcycle all the time as my main transportation (even in winter).
I think what jousters do is cool, and am full willing to watch and support you, but it's not something I will ever love enough to spend the $100,000+ to even start to get good enough.
I do have something to bring though for I am an excellent cook & baker. Surly Jousting is hungry work?