Your local hairdresser has an intimate relationship with their clientele. 

They talk about all kinds of things from local news to the state of the economy. 

They make awesome brand ambassadors! If you can make promoting your offer to their clients advantageous to them. 

Provide them with an app that includes a free sample of your services and maybe even a coupon for theirs. 

We call this piggyback marketing.
  
A low-cost market entry strategy in which two or more firms represent one another's complementary (but non-competing) products in their respective markets.” Companies have engaged in piggyback marketing for a long time in a lot of different ways. 

Before the advent of the internet businesses partnered on flyers, mail outs and more. 
 

Partnering on an app is a low-cost, evergreen method of piggyback marketing right for the market today.