I'm not even a local and this has me thinking of a better way. LOL!
1. DSF issues a membership card. Each card has it's own member number.
2. DSF only allows one pin per person.
2. DSF uses Rafflecopter (or similar) on their website as a way to sign up, draw winners, as well as contact winners via email.
3. Winners show up with their winner email and their membership card to pick up pin.
4. DSF verifies membership number listed on card to their Rafflecopter winner list, issues pin accordingly and "check off" that person as picked up.
5. Winners have X numbered of days to pick up their pin or they will be placed in store for sale.
If you aren't familiar with Rafflecopter, it is a free tool that is generally used to run online giveaways but it can be easily modified for a person's own needs. Not that I'm trying to shamelessly plug my own business but I use it for a weekly giveaway on my online store. You can see an example of it in action here:
http://www.diaperjunction.com/012513-FYSF-Win-a-GroVia-Sampler-Cloth-Diaper-Package_b_534.html
We have modified so that a person has a way to receive multiple entries to win but DSF can have just one way to enter and that is by entering your member ID number.
DSF could even build on this to generate sales. For example, they could allow extra entires for a better chance to get a pin or or even multiple pins. For example, if a person makes some sort of purchase (merchandise or food) in the store within a certain time frame, they could enter their receipt number as an added entry. I could see for hot releases someone making a daily visit to DSF to buy something for a chance to earn extra entries. I know I would if I lived close enough.