Getting clients is one thing. Opening a full-blown recording studio, even a small one, has a lot of other factors you need to consider.
1) You need a solid business plan.
Sales projections, profitability calculations, budget plans. Be optimistic. If you're not sure about your plan, no-one will buy it. Get an expert to help you here unless you're willing to do some proper research on the subject.
2) You need funding.
Commercial properties can be expensive to purchase, rent and/or keep running. Building the studio itself requires money. Lots of it. To get funding, you need that solid business plan you wrote. Otherwise they'll laugh at your face at the bank. In fact, they will probably do that anyway, since starting a recording studio from the ground-up isn't exactly a gold mine these days. Prepare to be convincing and persistent as hell even if you're constantly turned down.
3) You need to take care of the bureaucracy.
Zoning laws. Commercial facility building requirements. Compulsory insurances. Taxing. Accounting. Running a business is an endless jungle of bureaucratic bullshit. Again, get an expert to help you here.
4) You need to be realistic.
Do you honestly believe you will be able to turn the investment into profit? How long will it take? Are you sure you have charted all the expenses? Are you ready to lose sleep and eat macaroni for the next two years to keep the business running?
5) You need a plan B.
What if you fail? Can you still handle the debt or is the financial side of your life ruined forever? How are you going to keep yourself busy and pay the rent when the studio has five weeks of sudden downtime? Can you pick some extra hours at a local construction site? Do you have a degree that can get you work in a different field?
I might sound pessimistic and bitter, but I've been where you are now and spent a good couple of years scouting for buildings, talking with investors, trying to convince the bank, writing business plans, asking for help, spending many a sleepless night rolling in bed and thinking over some details that might make or break the plan. In the end, I came to the conclusion that starting a medium-sized recording studio from the ground-up is a complete financial suicide. That's pretty much what the investors were telling me from day one, and after all that work I had done I just had to accept it.
Instead, I went the post production route. Much smaller debt, much smaller financial risk, much smaller overhead.
I'm not saying you shouldn't do it. But if you do, you can't be just an audio enthusiast with a burning passion for your work. You need to be a solid business man as well.
Whatever you decide, I wish you best of luck!
