I'd expect you want this to be a fairly durable label so that in itself will make it a bit costly to do anything more than write on the liner with a laundry marker.

You could probably find a shop with an embroidering machine that could do some very basic generic tags for you. Similar to a patch where you provide the cloth for the backing and they just stitch the same generic pattern on it and you cut to size and shape desired.

or get some computer heat transfer paper that you could make an iron-on out off and create your own iron-on label. Not very permanent in the wash I'd bet but may do the job if you never put it in a washing machine.