[ame=http://www.amazon.com/DetMar-LINE-BLOWER-7-5-1-Reference/dp/B001DDSIL6]Amazon.com: DetMar IN-LINE BLOWER 4" 223/CFM 7-5-1 BULK (Image for Reference): Sports & Outdoors[/ame] sounds to good to be true
1000W kick out a lot of heat. I don't know if I'd trust a plastic fan to do the job. Don't forget it's better to pull the air and not push it so all that heat would be going through that plastic fan. I wouldn't do it. Plus 200 cfm sounds awfully low for a 1,000W light.
Are you talking about that lamp in an air-cooled hood/cooltube, or just venting the grow space? I think you will want at least 6" diameter to try to cool a 1kw lamp, 8" even better.