To be honest I don't know much about Online Schreibgeräte pen company. It was founded in 1991 by Alexandra and Thomas Batsch. It seems they're quite popular in some countries and their products are rather good. I haven't however, tried any of their pens. I've managed to take samples of two of their inks from a friend.
The company offers six inks in funny and small bottles that contain 15 ml of liquid. I would sat that for 3,95 euro / ml they're not cheap:
http://imageshack.com/a/img901/7333/8GPsUN.jpg
www.online.pen.de
I was able to put my hands on Samaragd and Rubin Red. Both are well behaved ink, however I'm not really keen on colors.
Rubin Red is rather boring shade of red. Decent ink in general, but there's just nothing special about it.
Bottle
http://imageshack.com/a/img910/5172/RMufEv.jpg
Ink splash
http://imageshack.com/a/img537/3867/v5RAWU.jpg
Drops of ink on kitchen towel
http://imageshack.com/a/img673/4291/kMnhig.jpg
Waterproofness
http://imageshack.com/a/img537/8563/bvSy1T.jpg
Software ID
http://imageshack.com/a/img910/3886/mF9KX5.jpg
Semikolon, Lamy 2000, Lamy Al-Star, M
http://imageshack.com/a/img913/4054/E4a4G4.jpg
http://imageshack.com/a/img901/7030/7g5hNV.jpg
I know it's not a lot of scans but I didn't manage to make good photos of this one and the small sample is gone