Someone on some other site pointed this out. though she's a peasant and lives on a farm, Mulan does seem pretty well off. They eat well, dress very nicely, have a set of good armor and weapons, have a nice amount of land (enough that they even have their own temple for their ancestors), and really could afford to get Mulan dolled up for the matchmaker (because I assume there's some payment involved). so I'd say she's far from poor, almost rich for a farmgirl but not quite.

They seemed to have a modest little farm, with enough to put food on the table, but nothing extravagant or fancy.

They didn't have any servants though it seems like Mulan and her mother were only ones suitable for hard work but they still had ancestors temple etc. And considering Mulan's ancestors, there were farmers, soldiers, that calculating man (probably scholar) and acupuncturists, they seem quite respectful well being family as Fa Zhou was also a war hero but I don't think they are extremely rich.