The hunt for is a right of passage for many network admins. While Aruba does not host a public "download for anyone" server, the firmware is legally obtainable at zero cost through trial accounts, ownership transfers, and eventually, public EOL archives.
The primary official source is asp.arubanetworks.com. You will need to register an account with a business/domain-owned email to download most images. aruba iap 207 firmware free