I used to think that Guzzla. Dan and I created our own home gym, and it worked for 6 months, worked well, but then it fell in a heap. Someone cant train for a few weeks for whatever reason and that affects the other people because thers is less atmosphere in the garage, perhaps no atmosphere if your lifting alone.
Now I dont know what they do at animal kingdom or strength republic but at our gym, members dont just pay to come in and use the range of equipment, they are also paying for coaching etc. And they also inherit a great environment, friends and a sense of team. Its a club really. You dont get that in a home gym. Of course everyone needs different levels of assistance, by no one is above improving.
Like I said the justification for our home gym was the same as yours, but the equation was wrong. We didnt factor in environment, team, coaching, atmosphere etc. etc.
It might work differently for you, it does for a lot of other people, but that wasnt our experience.
For the record, I think strength republic looks awesome.