Although you can save a lot of money buying on line from well-reviewed companies, Real hearing aids (Custom programmed by Audiologists) are still costly. Doing your research is the key.

First of all, you should read this article from the Federal Trade Commission. "Four Ways to Avoid Hearing Aid Scams". That will you a high level view to help get you started.

What are you really buying? 

Custom Programming by an Audiologist. This is critical. An Audiologist is a licensed doctor with many years of training. They custom program the hearing aids to meet the specific needs defined by your hearing test. If you have issues or your hearing changes in the future, they can update the programming to ensure your hearing aids are always getting you what you need. 

Technology.  Although hearing aids can look very similar on the outside, it is what you can’t see on the inside that will lead to the hearing clarity and convenience of use everyone seeks. A recent clinical study demonstrates the significantly improved benefit patients received from premium, versus basic, hearing aids

• Programmable Bands or Channels - This is the number of sound frequency bands that an Audiologist uses to program your hearing aids to the results of your hearing test. Up to a point, the greater the number of bands, the better the sound clarity for the user.  A more basic hearing aid will have 8-12 bands/channels while high performance models will have around 20 bands/channels.
  
  
• Automatic Environment Detection – This software automatically identifies and adjusts to changes in your sound environment (e.g., from a quiet car to a noisy restaurant), so no manual adjustments are needed. Higher performance (20 Channel) models will automatically recognize and adjust to a greater number of environments than lower (8-12 Channel models)
  
  
• Speech Identification and Clarity in the presence of background noise – This technology enables optimal speech understanding in noisy or group situations by a) Stopping the amplification of background noise and b) Dynamically scanning your listening environment to focus on the active speaker in your immediate vicinity. This software is significantly more effective on higher performance (20 channel) models than on lower performance (12 Channel) models.
  

Service. Good customer service providers will be accessible 7 days a week – and should be able to solve most of your issues immediately over the phone, without an appointment.  Make sure to ask if there will be additional costs for adjustments and re-programming and how long you should expect to wait for an appointment or a call back from an Audiologist.

Warranty.  With a small amount of daily care, most hearing aid users should expect their premium hearing aids to last 5 years or longer, so the length and quality of the warranty offered is extremely important.   

• Look for a 3 year warranty. This is the longest generally available and will ensure you are not hit with repair costs soon after purchase.
  
  
• Make certain that manufacturer's warranty will cover all defects including the replacement of rechargeable batteries.
  
  
• Ask if there will be a charge for reprogramming or adjustments during the warranty period – and what these costs will be after the warranty has expired. 
  
  
• If you are purchasing hearing aids with rechargeable batteries, make sure you understand what will happen when rechargeable batteries reach the end of their life. Can they be replaced or will you need new aids?
  
  
• Check the Loss and Damage Policy.  Ask what will be covered if this happens to you during the warranty period.

One helpful tool is the 'google' the reviews of brand you are considering (eg. Embrace Hearing Reviews). Read the reviews on 3rd party websites.