I have used Silver spurs once 3 years ago and it was reasonable and great. This review is based on an inquiry I made.
I called back to book another tour and they said they are no longer taking tours from the public, except it is a private tour. She said it will cost a lot for 2 people only. I wanted to go from Phoenix to the Grand Canyon. So I asked 'what about if I get 2 other people to join us. She said, it will cost me a little over $1000 each. I said $4000 for 4 or $4000 for 2 either way. I will use a different company that charges a lot lesser.