Its nice to own one, but its not the end of the world if you don't. Analyzers are a verification of whats in there (ie you request 32%, the analysis should come within 1% of the target percentage). Its not the other way around (request "nitrox" and check to see what it is). If you use this method, its ok to use another person's/shop's analyzer.
I made my own for about a hundred bucks. Oxycheq.com has a little kit called the "El Cheapo". It took me almost no time to make it, and it works great. Plus, you get to learn how analyzers work.