Dannis , if you are looking for Spiderman by Danny Elfman (complete orquestral score) I think you won´t find it [img]images/icons/frown.gif[/img] Sorry. About ET and AI try www.halleonard.com , they have a lot of John Williams`s scores [img]images/icons/wink.gif[/img] . Send them an email!!!
Truespec/alexander publishing is the place to start. If you go to Hal Leonard, they will just send you to a dealer like truespec. They have lots of John Williams signature series scores.
The ET score is from a suite and does not match the movie sound track. However, if you get the John Williams/Steven Speilberg collaboration compilation album, that is the version that is on the score you would get.