I have a 4x4x8 grow tent. It has heavy duty mylar in it. Bought it on amazon for around 100$. Here is the link: http://www.amazon.com/Mylar-HYDROPONIC-48x48x76-LEDwholesalers-GYO1008/dp/B002V9PBXO/ref=sr_1_15?ie=UTF8&qid=1297990080&sr=8-15
Just got one off Amazon, 106 with the free shipping. 4 by 4 by 7 tall. http://www.amazon.com/LED-Wholesalers-GYO1008-Reflective-Hydroponic/dp/B002V9PBXO/ref=sr_1_1?ie=UTF8&qid=1320964973&sr=8-1