A trademark cost roughtly $350.00. Not worth the $$ unless you're doing some major business. Trademarks are public domain and you can find who has what trademarked via the gov't. Just google "trademark register" with .gov domains, it shouldn't be hard to find.
I've just recently gone into business with my studio and I'm finding that the business aspects take care of themselves, that music is what matters... Once every few weeks you gotta make sure your website is still working (in my case, check to see if the guy you're paying a case of beer to has uploaded it yet) and give a call to whoever you're advertising with and tell them to keep running the ad. Get some business cards, go around town and hand them out at jams, open mics, to street musicians, if a band has a descent followng, offer to record them for free, just b/c there's a chance they might get big and you could reap some benefits from that.
If you're serious about becoming self employed, quit your job and find a descent paying part time job with a set schedule. I've just done this and now the amount of time I spend with audio and with musicians has gone up substantially... I'm not making quite as much as I was working full time, but at the current pace I should be soon. One other thing, get rid of your TV, I used to just beach out and watch tv instead of working on music, now, the TV is in the bedroom and I watch only about a half an hour a day when I'm going to bed. That's my 2 cents on starting up a small business.