From HacDC Wiki

We approved the purchase of business cards for the HacDC board and TimS bought some LivingSocial/Groupon discounts for VistaPrint to print them. Here are the Inkscape design files: Front and Back.

The coupons actually do help on the price but not as much as one might think because larger percentage discounts are available without them. Net cost was about $17 for 250 glossy two-sided color cards or 500 matte cards.

The QR code was generated by which I found gave a smaller payload than