Yeah, there are a number of ways we can come at this, and all of them are interesting. That's why it's fun not to have it all figured out at the get-go; people coming on to a project often make up better stuff than the first writer thinks of.
was a small, privately owned vessel. It's possible that there are economies involved in the sail arrangement that put FTL vessels within the budgets of small businesses. As I understand it, either the back story or some later elaboration of the Firefly
continuity had ships like Serenity
being built in numbers and sold at costs that families and small colonizing groups could afford - it was a kind of cheap reliable workhorse.