Here's another one I did - partnered with 3 other CFIs and we each kicked in $150 ($600 total cost) to purchase a booth at a local weekend home and garden show in my city. We made sure someone staffed the booth all weekend (several thousand attendees). We handed out learn to fly brochures (obtained free from Gleim) along with our business cards and an invite for an introductory lesson. We placed a TV and VHS player on our table and ran looped aviation footage to attract attention.

Many of the people that attend home and garden shows are looking for additions, hot tubs, pools, remodeling, etc., i.e. stuff that's not cheap. Hence, they've got some money to spend. The other market there is business owners that exhibit. High end luxury home builders have some nice disposable income to put towards flying lessons. Several students (or even lessons) from the event made the weekend and the $150 worth it.

Most of my experience is in part 61 schools not associated with a university or professional tract pilots, so I had to survive generating students across the spectrum. I've had everyone from a female police officer to a zookeeper.