If it's too good to be true, it probably is.
When I open up the Chicago Tribune most days, there are numerous one page ads for hearing aids. Buyer beware. Much of what you see is to get you to pick up the phone and schedule an appointment. Yes, most businesses advertise because it is a way sell their products and services. I'm here to tell you not to be fooled.
If the ad touts low prices, an unusual product, or asks for volunteers to do research, it is a gimmick. What looks like a good price will probably never get offered. Most likely, a different product will be recommended in lieu of what you actually came in for. It may be that the product of interest would not be right for you. But it got you in the door.
There are no new hearing aids on the market for "research" because this actually only takes place at a manufacturer's test lab or on rare occasions when a practice is doing a "Beta" test. And these products are not for sale.
You will occasionally see "out of stock", "low stock" or a limit to the number of participants needed at each location. There are so many tricks which are merely a way to peak your interest.
Take the time to do a little research on where you are going. Look at Yelp and Google reviews. Use your instincts. If it doesn't feel right, it's not the right place for you to start your journey to better hearing.