My way of looking at it is to buy all the Sierra CD-ROM games off eBay, because you will most likely not find those on the net (due to being several CD’s each) and to download the older ones that I don’t have (I have originals for most of the old KQ,PQ games). I got every single Sierra talkie game off eBay last year, some of them new (budget release jewel case only versions), and it cost me about $100 U.S. including shipping.
A tip to those of you trying to find the old games in google – instead of searching for “kings quest 4 download” or something like that just type in the filename. E.g. “kq4.zip” – this is a more reliable way of finding them.
And I would recommend people looked on eBay as there were tonnes of Kings Quest and Space Quest collections available on there last time I looked, and they were pretty well priced too.