I have my own domain name for my Etsy blog (www.bookgeekery.com) however, we don't have our own domain name for our (my mom and i) blog about my brother's autism.
i think it's a good idea to have your own domain name, especially if you have a shop with the same title. it just looks more professional. however, i don't think it's needed for "everyday blogs".
I like having my bookgeekery.com, it's easy and sounds more professional. Plus, only 10 dollars a year from blogger... that's like nothing!