May I humbly suggest that the problem you all encounter is more than just a simple 'supply and demand' problem' It is perhaps arguable that there are too many instructors chasing the limited number of customers (many of whom are the wannabes) however the industry is a little like the foolishness of farming.
The farmer goes out and ploughs his fields, sows the corn and then watches it grow through the vagaries of unpredictable winter spring & summer in the hope that it will yield well at a price unknown till he comes to sell. (ok , so there are forward contracts)
Basically, loads of people hanker to fly, so they go and spend their hard earned or borrowed cash to pursue a dream, but without any guarantee of the rewards they aspire to at the end of the day. We all love to fly and will (or almost) prostitute ourselves to follow the vocation. Consequently, those following the instructional route to hour building etc are victims of their own weakness. A union might sound like a good idea, but with such a fragmented industry I don't believe it would work, because too many will continue to follow self interest to reach their goal, particularly as a considerable sum will have already been invested in the dream.
I am fortunate that I do not have to be a paid pilot to fly, but I sincerely wish you all good fortune in attaining the honey pot !