Do you have to use the silver insulated flexible ducting for my exhaust and intake, or can I get away with something like this?... 6 INCH x 16 ft FLEXIBLE INLINE FAN BLOWER DUCTING DUCT - eBay (item 300350045937 end time Oct-21-09 20:30:09 PDT) or this.. 6 INCH x 16 ft EXHAUST FAN BLOWER DUCTING DUCT w/ CLAMP - eBay (item 300350045914 end time Oct-21-09 20:30:04 PDT) A lot cheaper solutions...
You can use pretty much anything. Here's some cheaper stuff yet: C.A.P. Custom Automated Products: DUCT, 6 inch MYLAR & WIRE, 25FT, 516 [DUC-02] - Fans, Blowers & Ducting - Environmental Controllers, CO2 Generators, Fans, Blowers & Duct, Air Purification - Horticulture Source Note that smoother ducting will maximize your airflow and minimize noise, and that flexible ducting should only be used where necessary to accomodate movement (like air-cooled hoods that need to be raised and lowered).