And finally, the free option, find a native and make a trade. This is a weird option that has a couple of different ways of handling. You could make it a volunteer date and trade ESL help for foreign-language tutoring. You'll have to do research in your local community but opportunities exist out there. A great way for singles to learn a new language is to date someone who speaks the language you want to learn. Isn't this "duplicitous?" Sure, but is it any more duplicitous than only dating someone because you just want to sex them up or think they're rich and will buy you things? Read: One Love, Two Cultures: Making It Work
Like all massive undertakings, set goals and give yourself rewards. If you master conjugation of the present tense, regular Spanish verbs, treat yourself to a night of Vicky Cristina Barcelona and tapas (and Flamenco dancing, naturally). And when this bastard of a red-headed stepchild of an economy swings back in the other direction, try a vacation where you can speak a little of the local dialect. I know you feel stupid but the locals do appreciate the effort (except, in my experience, for a certain country between Germany and Great Britain).
Note: I do not recommend trying to learn just by watching subtitled films, I've seen Crouching Tiger, Hidden Dragon ten times and only know how to say "thank you" in Mandarin.