We noticed some European style license plates as we pulled in. On the way out, there was a guy with one on his bike in front of us on the on-ramp; he pulled over to let us pass him so the group he was with could catch up. I slowed down and asked him where he was from. "We are from Denmark." Yow. Consider what a Harley-Davidson costs in Denmark: quite aside from shipping and customs duties, it's probably twice the cost there of what it is here, and they're not exactly cheap here... Then consider that he had it shipped back to the US, then the trip to Sturgis and back to the port of entry, then shipping the bike back again to Denmark. That's one expensive vacation.
The other sight was one that made us both giggle: We got passed by a Harley with what looked for all the world like training wheels. Yes, outrigger wheels, mounted to the rear axle, riding on the ground. I haven't got the faintest idea why they were there.