monline

It took me a few minutes to find so it might be useful for others if I share. There are indeed pre-packaged source bundles for every Eclipse release available and theoretically you should be able to compile your own eclipse build fairly easily.

To get to the relevant page at eclipse.org, you've to follow this trail:

1. main eclipse.org page
2. main page for downloads
3. Older Versions of Eclipse (the link to this one is in the top right section of the previous page with the label "Looking for Older Versions ...")
4. Archived Eclipse Platform Releases

On the latter page select the release you're looking for and on the release page you'll find ZIP files of "Source Build" packages. Read the instructions (links besides the source build download links) on how to compile Eclipse from a Source Build.