It can be a little tricky running a site with both free assets, and paid assets. I tend to lean pretty heavily on the side of just giving everything away, but it's not really a great business model.
So, starting immediately I've begun bundling one additional vector asset in with every purchased vector pack. This additional vector will be pulled from a different pack currently for sale and won't overlap with any assets included in the previously posted Free Sample Pack.
I do have some additional ideas for getting more free vectors out there, including the rerelease of some very cool assets I created a while back, but for right now, I've decided to toss a bonus vector in with paid purchases.