I don't have an aircraft now but remember that in 2004-5 my fixed costs were more in the region of £10,000 per annum. (in the UK)
I would highly recommend that you share the aircraft with another person. It's not the cost but owning and flying your own aircraft can be a lonely business and there are times (many times) when you need to share worries, concerns and experiences. If you do your own maintenance a second body is invaluable and it is very nice when you are flying regularly if you know that someone else has done the checks as well - you can get into bad habits if you are the only one who ever does the routine checks.
Having said that, it is soooo nice climbing into your aircraft when the seats are as you left them, the cockpit clean, and it's all just as you want it.