The average cost for an offshore oil drilling rig is now about $650MM. The ones that can go really deep are even more expensive.
Aside, swiss watches tend to have a watch maker's four on them instead of the more correct IV... and apparently there are a bunch of other variations out there[1]. Though MM is still quite stupid.
1. https://en.wikipedia.org/wiki/Roman_numerals#Variant_forms
Not sure how someone got the idea to do that...