Aerofoil1,
Remind yourself that with similarities to a car, boat or house, when you buy a plane, you're buying into something large/complex/expensive enough, that it requires operational support from others, and they are entitled to be fairly paid for their time too. That means cost.
Airplanes, depending upon the nature of their authority to fly, bring along with them a "system" within which they operate. This system is intended to assure that they are safe to fly. It includes many of the aforementioned costs. Most everyone seems to assert that they expect the aircraft that they fly to be at least safe. Most pilots do not have the skill or capability to assure this on their own, and so have to pay for this to be done for them.
Though I very much encourage flying and owning, you gotta keep it within what you can afford, or it gets miserable for everyone. I have owned my C 150 for 25 years now. Yes, a "spam can" by newer spam shell standards, but it's a very nice one, and I don't even think about the operating costs. Other aircraft I fly would bankrupt me if I had to pay the expenses - I know my limits...
Yes, co ownership, or perhaps go back to your hour at a time aircraft rental organisation, and offer a hansome daily minimum, to take the plane for the day. Money talks, if they think that the aircraft might sit for part of that day anyway.
Welcome to the prospect of ownership, but 13,000 pounds is not realistic for sole ownership of an airworthy aircraft in the long run, unless you can mitigate all of the other associated costs.