We have a restaurant: our best advertising is: for tourists, TripAdvisor/Google Maps, free advertising by getting good reviews. Locals: Facebook, especially running competitions and boosting occasional posts, costing around £40 a month at the very most. Giving vouchers for various charities/local organisations raffles etc really increases word of mouth recommendations. Where we did try to spend money on advertising in, eg, local newspapers, adverts in local cinema, etc, the return was never worth the cost...
Just edited after reading your post, vouchers, offers might help you to start up to somehow? And Facebook too, with useful regular links/humour etc...