@Lawrence Gillett I am not a business broker, but as others have mentioned you usually want to look at revenue (EBITDA/etc. can start getting involved with bigger transactions but just use revenue). You can see what comps are possibly selling for based on that revenue stream (might be 1x or 3x - just depends).
I will say that a value add business is probably a bit more time consuming than a value add real estate project (just my 2 cents) but I don't think value is only based on what a property (or business) is currently doing. You as a buyer need to understand potential. I get that most properties are bought based on cash flow, but there have been so many transactions that I have been involved in where the prices we paid, if based on cash flow alone, would have never gotten the deal done. If there is a sweet upside that you can bring to the table, and just consider that and assign it a probability. Not saying others will necessarily pay that price, but if you can pull it off then you are still going to end up better than not getting it.
Take my thoughts here with a grain of salt as I have only seriously considered maybe buying 1 or two businesses and most of my experience is in real estate.