I myself do not have one as I sold off my Subtank but you may have some luck with OCD over at IBTanked I know he is making glass tubes for other tanks. Give him a shout. He a nice guy. http://www.ibtanked.com/ His prices are very good also. I know for the Erlkonigin it's $5 for a glass tube
I have not ordered anything from OCD in quite some time as I stopped using carto tanks over a year ago but it used to be about a week. Still quicker than ordering from FT. I only posted this in the event someone did not have one for immediate sale.