When I started dancing I was also on a very limited budget. If there is one piece of advice I would give, it would be to dance as much as possible. So how do you do that? Here are some ideas:
1. If you are able to take a class occasionally, make sure you go back home a practice the steps. Write down what you learned for future practices too.
2. Watch YouTube and try your best to mimic some of the steps. There are tons of videos including instructional.
3. Find someone you can practice with of either sex.
4. Get people's phone numbers and get your own social group going. Find out what they are doing too and see if you can participate.
5. Ask instructors if there is anything you can do to assist them in exchange for a free lesson like bring snacks, work the door, or pass out their flyers.
With enough commitment, you can learn to be a great dancer. Just don't allow yourself to get frustrated, or else you might lose your momentum. Realize it is possible and that given enough time your situation and dancing will improve.
Salsa is social dancing in the first place. You can meet the salsa crowd without any knowledge of the dance and the music. But you should be able to integrate into that community. Start at the edge. Your perfume should be subtle, your togs should be unobtrusively. Don´t present slogans and don´t make any fuss. Work yourself steadily way forward and ask questions that may help you. Somewhen a girl will complain about your restraint: don´t be so coy, come on, simply move to beat....
Forgot to say: No problem to start without any knowledge of salsa music. But ask the DJ for the names of the bands, try to recognize typical instruments, and so on..