[Cogito]

I've only played through once, but got 1.66B and felt I could probably get higher pretty easily.

My strategy was to initially buy high/sell low to get net value up so I could purchase higher value properties. By the time I could buy the most expensive properties I had stopped selling anything. Whenever a recession ended I would simply buy as many of the most expensive thing possible before the price raised too much. Similarly I would cancel any debts, and do any maintenance as soon as the bottom of the recession hit. Buying properties seemed to cancel the need to refurbish, but I haven't looked at how complex the logic is so I'm not sure.