Referral Feature - Choosing incentive structure

Haven't tried out the feature yet, but was curious about it since it's a thing that I was thinking about implementing.

In my line of business (Stairs and Railings) where there are no return visits and all jobs are one and done, I don't think that a lot of people would use this feature. 

If i change my mind about it I would probably offer $100 for a referral and do more for the jobs that are bigger. Let's be honest $10-$50 is not that much for a stair job that will land you a $2500.