An update to the Minimum Order add-on has just been released.
Parent/Child Minimum Orders
In this release, we added new features to work with parent/child galleries. If you set a minimum order amount on a parent gallery, the items in cart from the child galleries are used to determine if the minimum is set. Previously this add-on could only handle minimum orders on individual child galleries.
Order Subtotal Minimum
There is a new option which appears in Sunshine > Settings > Checkout where you can set a minimum on the cart subtotal.