Not sure what the difficulty finding a suitable M10 bolt is - there's any number of people on eBay selling these in any length and head type combination you'd ever want.

You can buy "buckets" of assorted fasteners in hex, socket or button head styles for not much. A £20 assortment would last you for years.

I use these guys when I want polished stainless fasteners with unusual head sizes;


http://www.polished-stainless.com/