I'm working with a nonprofit that is in need of wifi throughout the building.  They are a homeless shelter operating out of an old 1920's era home.  Because of the age, I'm not allowed to drill and run cables.  I figured with AP's it would be 5 AP's on each floor to cover 99% of the building.  

The problem is they are a nonprofit and need to get funding to do this. If I put AP's on the wall, I would need to run electrical lines close to the AP, and that might get costly.  My thought was to use "Powerline" adapters throughout the building.  The question is though, I needed 10 AP's for the two floors. Could I have one powerline adapter plugged into the router, and nine more throughout the building pulling off that one, or is that too many?