We don't use inhalers but, FWIW, have brought them back for friends from the UK (where some family lives), Canada and Mexico with no problems at all.
There are a number of things that, when we've had less-than-great employer coverage (long before the ACA and long before our current ACA plan) we found it was actually worth flying to Mexico, getting everything there, and sending it home. When flights were cheap, we would do a day trip or fold it into a vacation. Many more things are OTC there than here (like birth control which, depending on the pharmacist I got and their belief system, was often a protracted trial in the US), and you can also get a prescription legally in Mexico, very cheaply, at a farmacia. Then, mail a box of the inhalers and whatever else to your home in the US. That way there are no airport surprises.
Not even kidding about airfare AND the stuff costing less than our co-pay would have been, WITH insurance.
Best of luck! Happy to answer any questions if you have them.