If he can't afford a $100 RO unit, then I think he is in for a big financial surprise when he sets up his tank! :scared:
That asside, it all depends...
I would first have him fill up a white, 5 gallon bucket with water from the well and make sure it is not cloudy, yellow, green, orange, etc or has any visible sediment...you'd be surprised what you will find doing this. Good water should be very slightly blue. Any other color is a sign of dissolved something in the water. The "something" could really be anything with a well: rust, minerals, pollution, farm run-off, etc.
If all "looks" ok, I would have him take a sample to the LFS and have them test it for everything they can. He may also want a professional water tester to test it and tell him what is really in it just so he knows. Especially if this is the well he drinks from. We have a town here that was just told their well water is polluted from run-off from an old Air Base...very bad stuff....
As this is can be a very expensive hobby (again a RO/DI unti is well worth the investment), the last thing you want is for your water to be bad before you even put it in your tank.
As for the water conditioner the LFS is talking about they usually only take out chlorine. They are made to be used with Tap water really...not well water.
I guess the short answer is "yes" he can use it, but I would be very careful and test the HECK out of it before doing so.