Trade publications like nursery association magazines talk about industry trends. Information specific to your business I don't think you will find anywhere except in the history of your business.

The current owners of what? A land holding, structures, a home with backyard plantings? Were they willing to actually show you their tax figures and accounts?

I firmly believe in business plans, and revising them as your business grows. But, I did not borrow for my capital and they were more for my own use (and I did review them, it keeps an owner in touch with reality). If you are planning to use it for accessing capital with which to set up your business, those dollar figures will need a history of 'what you are taking over' as a base for what you hope to do with it.

Interstate sales of plant material is regulated, and local sales of perennial stock is also regulated by the Department of agriculture as well. Add zoning and sales taxes to it and I'm hoping you are assuming a legitimate business venture and not somebody's hobby. Because if they didn't legally treat is as a business, it will come out. And finally, what is your experience with growing them?

The government actually has that information on hand, some of which is gleaned from annual, obligatory floriculture surveys. I just filled mine out this month. Talk to your local extension agent if you are considering entering the green trade. It's pretty much like pregnancy. You usually can't have a toe in it. You jump in whole heartedly or stay out of the water.

Good luck, I wish you success.