You already know how the "used" machine sews. When you open a box with a new machine, they don't always work as they should. May be only a small chance but, is still a possibility. Just a thought.
If you buy the one in the other state, be prepared to take it back there for service.
Businesses work on money. We own our business and believe me people are always trying to take advantage. We don't encourage walk ins as they are not our usual customers. We sell to companies in the industries, they know more about what they need and the vast majority are honest.
Just my opinion.