Word of mouth is the only marketing you never pay for, and it travels by voice. If someone has to spell your business name to a friend, or explain the pun, or clarify which of two similar spellings you use, you have put a toll booth on the one channel that was free.
Say the name out loud to somebody who has never seen it written down, then ask them to find you online. Whatever they type is your real name. Buy that domain too.