I doubt that this machine has much value. I often see this style of machine in thrift shops for $25 or less. Only some of the old machines are considered collectibles -- mostly black Singers and old Berninas. I don't think the Brother machines are considered collectible.
You might want to join a vintage sewing machine group at
http://groups.yahoo.com , especially if you can find one for Brother machines, and ask there to be sure.