I just messaged T Markus customs to learn more about their tank coating. Also, I was searching for metal tanks when I came across this thread with lots of information
www. ducati monster forum .org/index.php?topic=25074.0
be sure to delete the spaces, i don't know why this stupid forum won't let me put the full link in
also, here is the only metal tank i found
http://www.moto-works.jp/beater/index.html
I'll save you the conversion, 173000 yen is about $2100