Can counter words also be nouns?


According to people I've asked, and [this
page](http://www.sf.airnet.ne.jp/~ts/japanese/counter.html), if I pay 20
Australian dollars for my meal, it seems I say ni ju doru (20-ドル), and that ni
ju-en doru (20-えん-ドル) would be ungrammatical - "dollar" acts as the counter.

Is it possible to refer to the Australian dollar as a noun in other
circumstances (eg while talking about how the dollar fared on the exchange
market)? If so, is this only because it's a loanword, or can the same apply
with native Japanese words?




A quick Google search brought me to [this Amazon
page](http://www.amazon.co.jp/%E5%BC%B7%E3%81%84%E5%86%86%E3%81%AF%E6%97%A5%E6%9C%AC%E3%81%AE%E5%9B%BD%E7%9B%8A-%E6%A6%8A%E5%8E%9F-%E8%8B%B1%E8%B3%87/dp/4492395008)
for a book with title 「強い円は日本の国益」, which is an example where the counter for
Japanese Yen 円 is used as a noun to refer to the currency unit, thus I believe
counter words for currencies can be used as nouns.

![enter image description here](https://i.stack.imgur.com/fj2VB.jpg)

EDIT: StackExchange engine breaks the Amazon Japan link again so here are the
raw URL (you need to copy-paste):
<http://www.amazon.co.jp/%E5%BC%B7%E3%81%84%E5%86%86%E3%81%AF%E6%97%A5%E6%9C%AC%E3%81%AE%E5%9B%BD%E7%9B%8A-%E6%A6%8A%E5%8E%9F-%E8%8B%B1%E8%B3%87/dp/4492395008>




A quick Google search brought me to [this Amazon
page](http://www.amazon.co.jp/%E5%BC%B7%E3%81%84%E5%86%86%E3%81%AF%E6%97%A5%E6%9C%AC%E3%81%AE%E5%9B%BD%E7%9B%8A-%E6%A6%8A%E5%8E%9F-%E8%8B%B1%E8%B3%87/dp/4492395008)
for a book with title 「強い円は日本の国益」, which is an example where the counter for
Japanese Yen 円 is used as a noun to refer to the currency unit, thus I believe
counter words for currencies can be used as nouns.

![enter image description here](https://i.stack.imgur.com/fj2VB.jpg)

EDIT: StackExchange engine breaks the Amazon Japan link again so here are the
raw URL (you need to copy-paste):
<http://www.amazon.co.jp/%E5%BC%B7%E3%81%84%E5%86%86%E3%81%AF%E6%97%A5%E6%9C%AC%E3%81%AE%E5%9B%BD%E7%9B%8A-%E6%A6%8A%E5%8E%9F-%E8%8B%B1%E8%B3%87/dp/4492395008>

