> No, it isn't. At those odds, your expected wait to marry is over 16 years, which defeats the purpose.
Most people who are motivated to get married explore more than one option at the same time. So you do this plus some combination of other things likely to get you socializing with members of the other gender: start doing the weekly ski/ bike trips; going to pubs; going to yoga; join the square dancing club, etc etc. (Clearly my recent experience socializing with the opposite gender is pretty badly out of date).
Again, nothing legal/ ethical and guaranteed so the only way to increase the odds is to increase your exposure to your audience. If your goal is marriage, $120 and 6% on eHarmony is price and time competitive. Though likely not as fun as going on weekly ski or bike trips.