Well for some reason that pic on the home depot website is not displaying for me. Tried two different browsers. Anywho, the poly is great and you can find it cheap on ebay or at your local hydro store. I would definitely recommend getting some fans for ventilation. I found a great deal online for two 160 cfm duct fans for $50 bucks on ebay. They work great, for my small temporary space. You will definitely need ventilation if you are running a 600w hps, if you don't your plants will burn and you won't be getting anything out of them.
http://www.ebay.com/itm/2-pcs-6-INLINE-DUCT-FAN-EXAUST-BOOSTER-BLOWER-250cfm-AIR-COOL-BOOST-Six-Inch-x2-/160710627226?pt=LH_DefaultDomain_0&hash=item256b198f9a here is the link
http://www.ebay.com/itm/2-pcs-6-INLINE-DUCT-FAN-EXAUST-BOOSTER-BLOWER-250cfm-AIR-COOL-BOOST-Six-Inch-x2-/160710627226?pt=LH_DefaultDomain_0&hash=item256b198f9a here is the link