Have a look here...but as Gary said, they're prohibitively expensive!
I have some similar countersunk bolts, but unfortunately, they're not metric/allen head.
http://www.pro-bolt.com/titanium/titanium-bolts-countersunk-washers/titanium-countersunk-bolt-m5-x-0-8mm-x-10mm.html#.UYgLbYZuvVU