Im on my phone atm so sorry for quoting all of this.  
 
	 
 
	You probably low on the 300 mil estimate.  Most of my level 50 retirees end up at that level, and they really aren't in the solo 54x8 class without at least some help.  
 
	 
 
	At a billion inf though, its a snap.  
 
	 
 
	There is no IO decay, there are no maintenance costs, etc.
 
	 
 
	The only check on people reaching that level is boredom altitis or a lack of focus.  
 
	 
 
	A billion isn't even that much.  If you solo through arcs to 50 you'll be halfway there.