As for sierra's old adventure games they are now being sold for 19.99 at Gamestops and I am sure other places as well in compelation packs. The games they selling I have seen are
King Quest 1-7
http://www.sierra.com/en/home/games/game_i...xsZWN0aW9u.html
Space Quest 1-6(I believe)-
http://www.sierra.com/en/home/games/game_i...NlX3F1ZXN0.html
Leasiure Suit Larry1-5
http://www.sierra.com/en/home/games/game_i...orm-global.html