Downloadable / Useable Red Alert (2) audio clips?
I once downloaded an archive called 'Command and Conquer Anniversary Classic Ringtones.rar' containing 7 audio clips from RA, RA2, C&C1 and RA3. I think I downloaded it from the official site.
It doesn't have 'construction complete' though, but other classics like 'Got a present for ya' and 'Shake it baby!'. Since it was free and legal and all that, I'd be happy to give it to you, if you'd like that.
Use the XCC Utilities in order to extract the sounds you want from the resource files (you want the XCC AV Player and sounds.mix, IIRC).