Def cooling fan....
My main point of this post is you dont "need" an "astro" cooling fan.
Places such as MSY, Umart, Ebay, PC case gear etc all sell good priced pc fans usually an 80mm or 120mm is what you need.
if you scope already is powered then ur set, make a simple connector for the 12v and ur good to go. if its not powered then an astro fan maybe a good choice. Or you can diy for around $20..
This power adapter.
http://cgi.ebay.com.au/Car-Wall-Char...item2eb3f3e9ed
Cut the end off this socket.
http://www.jaycar.com.au/productView...g&form=KEYWORD
Then cut the plug off this fan and join it to the cut end of the socket.
http://cgi.ebay.com.au/80mm-Cooling-...item2eb11ad014
OR put this plug on the end of the fan
http://www.jaycar.com.au/productView...e&form=KEYWORD
Total cost around $15
I can make it for you if you want, OR if you in brissy i can show you how to make it if you are serious I can do a better diagram.