Lots of manufacturers say that their cranks are available in 165mm, but very few online retailers offer this option. You'll either have to look around real hard, or get your local bike shop to special order it for you, and so pay a bit more.
It appears that the biggest online bike store in Europe stocks quite a few of these. Have a look at
this page and use your browser's search function (hit Ctrl-F) to find all instances of the term '165' on that page. Some are even listed as in stock.