You can quickly produce a lot of cuttings from a new plant especially if you buy from ARE, their plants are huge. The first year you should be able to take a few cuttings, let's say five. If you're good at growing, these five cuttings they should be nice looking 1 gallons by next year. So next year you take 10 cuttings from your original plant and five from each of your new plants. Now you have 36 plants. It literally increases exponentially from here. Cuttings from young plants root so much better than cuttings from older plants that have been cut too often.
Join a local rose society, members throw away tons of potential cuttings when they prune their plants.
Producing new plants is a craft as much as a science. If you can get a job in a nursery that does their own propagating, you can learn a tremendous amount in a short time.
There is plenty of money to be made in both the landscape and nursery industries. A love of plants is essential. Don't be afraid to hire experts for areas that you are not expert in, maybe for example you might need help with taxes, licensing or getting a tax number . You do not need to know it all to succeed.
Q