If one has a shop, with employee's, do more than 5 or 6 cars a week, can not recommend having them enough!
They will pay for their cost in a year, just on product savings and keeps the employee's from improperly mixing products, too strong, not enough, the "we always just did this or that at the last place I worked" etc.
Over the years, going back to 1989, when ever we set up a shop for a client, when we did the Driver's Mart chain,(now part of AutoNation), when we set up all the Delta Sonic Detail Centers, when we set up the Mazda de Mexico Body Shop Detail facilities, we put in mix stations.
Two main suppliers of these units, but can't recall either name right now.
Need at least a 3 station unit, glass cleaner, all purpose and carwash concentrates.
You can start with one though and connect them together, in the training video for the ABC system on the Valugard.net site is Tim using one to mix the products for using the system.
Like I said, would NEVER have a shop and allow the workers to mix on their own.