Lead,
If your dad is using these in a fairly gentle manner, I would look at high quality porro prism glass (the ones with the eyeholes that are NOT in a straight line with the objective).
These are going to offer higher quality at much lower cost than roof prism 'nocs.
You can get Leupold, Nikon, Steiner and others at much better prices.
The downside is a little more bulk and a little less weather resistance.
For armchairs or window sills, the better choice.
If you don't buy local, try riflescopes.com.