Everything is scalable - do your research and try to think what your market would be? What standard of recording they would expect? Do you need to start with a million dollar studio - or something small and scalable? Then grow as your clientele grows.
I think there is an underdeveloped market for live recording of small scale bands and I think the technology is getting better/cheaper everyday to do this.
As more small business get into Web 2.0, people will want to make quality Podcasts, but will not have money for bigger studio - it might be a niche that could become your bread and butter.
Check out your community for earning potential other than the traditional ‘music’ recording. Also consider developing your web skills so you can advise on web-distribution of contnet and design hosting. You'll want a web presence for your studio anyway.
Start to go and watch solo artists, bands, classical musicians, stand-up comedians anyone who might want to record and start to build relationships. Be willing to do a bit of free just to get ‘feet through your door’. Join your local chamber of commerce.
Who is your competition: direct and indirect? Try to find a gap in the market and clearly differentiate yourself from them.
What is your skill set? Have you trained as a sound engineer or worked in recording studios before? If you haven't then you definitely need to get in and learn from others.
Talk to your bank manager often they are happy to provide guidance. Think about the current economic climate; is it the right time to go out on your own? Would it be better to build your skill set and reputation with someone else? Do you need to go for it all at once? Develop a transition plan from current life to life as a studio owner (3 years is a good time frame).
Be resilient, persistent, optimistic and creative.
Good luck
Burt