A trademark like MyDomainMark.com or with a logo and words is not as strong as just the words, like, My Domain Mark. For the most protection you want to register just the letters in the order you want. If you only had the trademark name in .com, a trademark with .net or with out any web address extension has a good chance to pass for a registered mark.
Save money, do some research. NOLO.com has books written by Lawyers that cover most questions, legal, how to and tips. Go to nolo search and type trademarks. I found this
http://www.nolo.com/legal-encycloped...ial-29049.html You might end up doing it your self and have no problems. If you do have a problem then seek a professional help, you might save some money.
This is not legal advice or the best way to get exactly what you want with out a trademark lawyer.