Opening your own business takes a LOT more than just finding out the price of wholesale fabric and the profit you could make. For your profit margin you have ALL the business expenses to consider. Rent of the building, insurance, displays, power, phone, price of credit card acceptance... and so much more.
I would love to open my own shop, husband would be behind me all the way on it. The first thing that got me was the price of wholesale fabrics. The reason quilt shops charge so much per yard is that they have to pay so much themselves.
My husband and I have had our own business and I've managed/directed one or two. Self employment is a 24/7 job.
Do LOTS of investigating before you take that big step.
I haven't ruled out my own shop yet either. Would like to get into the longarm business too. Need to try one out first! LOL
Best of luck in your pursuit.