I can't remember the last time I had less than a 70 hour work week. so I have to prioritize any spare time to try to get the most enjoyment possible out of it. To spend two hours a day in the shop I have to cut back to 6 hours a day of sleep before a 14-hour night shift.
One of my common decision points in choosing to buy a ready to go plane versus one to restore is if one has more time or more money. Apparently you time is very limited. Hopefully you are being paid well for working so many hours. In your case it may be better to purchase a plane from Lee Valley or Lie-Nielssen. The only way a used plane would be a good investment for you is if it comes from someone who will set it up before sending it to you. As Pete mentions even used planes from reliable vendors will likely need at least having their blade sharpened. In the future you will likely have to sharpen your own blades.
jtk
"A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
- Sir Winston Churchill (1874-1965)