I don’t know what you spend to reach a potential customer, but I bet it’s more than $5. How much more would you spend if you could get a live prospect in your office for an hour?
I love this simple promotion from REI. They offer free lunchtime seminars, and everyone gets a Chipotle burrito. Both brands get great promotion and a ton of goodwill.
Is your marketing this simple? Are you making things too complicated?