Am i missing anything else?
Yes, all the little things adding up at least. I do keep full records of my SEP and for the current one I do have 450 list entries for about 3.5 years, so something like 130 items per year with costs attached (and I do purchase oil in 54 liters each quantities). Talk to somebody next to you and have a look in their books. How many hours a years do you plan to fly?