I have heard of this in our industry. I know that there is at least one company that does this.
At CBTA last year a company was talking about their downsizing and how they worked with a group for better buying power since their program has shrunk significantly. I did follow up with the company and they have a "interviewing" process to see what you can offer and what your needs are to match the group. For us I was looking at the office supplies bulk buying power since there isn't many options out there.