Acoustic treatment question: do you agree with Dennis Foley that $46k to $65k is required?

I have been using GIK products and have made use of their free advice as well. My experience has been one of gradual improvement as opposed to an all-at-once treatment. I can say this: something is better than nothing and I haven’t found ‘too much’ yet, though I certainly believe it is possible. 

Once I put in bass traps and took care of direct reflections from walls and ceiling, I added diffusers towards the back of my listening room, which, given the other improvements I’d already enjoyed, seemed remarkable. 

The main thing here, if you’re not doing some kind of professional room sound analysis anyway, is to try to fix the biggest problems first, and only then go after those smaller issue that remain. I don’t think one needs to spend a fortune.

I’d add that my experience has been that acoustic treatments can make any rig sound better, regardless of price.

It certainly doesn't have to cost that much to treat a room.

I was lucky enough to have a friend whose profession is building home theatre spaces, and he owns many thousands of dollars worth of audio instrumentation and software and he was kind enough to help me set up my combination listening room/home theatre.

I already had a false curved ceiling which helped on a couple of issues, and the one live wall made up of glass doors was happily handled by installing heavy optically opaque curtains which I needed for video anyway.

Many of the other issues were dealt with inexpensively. For instance two and a bit walls lined floor to ceiling with shelves of vinyl LPs make a great diffuser (and no, I did not stow them with every other album pulled out or pushed in although it would theoretically have enhanced diffusion.

Speaker set up was a mix of a ballpark area they needed to be in plus accurate measurement - me in a listening chair, him with a laser range finder to accurately position my chair and the speakers.  Ditto for the four surround speakers and two subwoofers.  

Undesirable echos were dealt with by things as simple as laying an antique carpet on the too live wood flooring.

Thanks @wwoodrum for your experiences. I have heard from several experienced people who added treatments early on only to find they didn't do anything. But, as you relate, adding more seemed to pull things into visible (or audible) range and then other work with diffusers, a bass array, etc. brought things home. But, at first, a lot of money for no results.

@wspohn  Yes, having that kind of help is invaluable! Good karma for you!

The answer is, 'Possibly' - you can spend less and you can spend more.
In my case, I spent $118K with Dennis for an unsatisfactory result.
It really depends on the room, and how difficult the existing acoustics will be to treat and the capabilities of the designer. If your room is pretty decent already, you may not need much to put the finishing touches on it. If your room presents difficult acoustic challenges, the spend can go way up as does the risk of as positive outcome.