well.....
my aluminium framed windows were pretty much unsuitable due to their frame and sliding design.
Hence I went the $$$ option
PVC frames and regular performance (no lowE) glass. Each window was around $1500 including removal of the old windows and installation.
I was so happy with their noise insulating performance that I did the front door as well. (double glazed PVC) my living room which has a truly massive window and our kitchen / tv room I did the double glazed sliding door as well. In all the cost was about $11K, sure this is a significant amount of money.
The alternatives were plastic hush kits which are basically a very expensive version of your DIY double glazed windows held on with magnetic strips.
That option was about 1/2-2/3 the price of the double glazing however from a sales perspective not anything like the real McCoy...
Am I happy with them? Hell yeah! worth every cent, workmanship impeccable and all done with no fuss.
To keep out the summer Western heat rollershutters installed on the West facing windows and that nails the heat coming in problem with a small insulating value in addition to physically stopping the light hitting the glass with a foam / aluminium sandwitch.
No good for noise as they claim though.
Had we not been so close to the airport
http://www.nearmap.com/?ll=-31.949606,115.952303&z=20&t=h&nmd=20110908 zoom back a couple of frames and you get the idea..
I would have attempted alternatives but as it happens being this close, noise was a huge issue and in all I've probably spent about $15K including noise insulating batts to keep it to a dull roar inside.