Hello fintuckyfarms,
If you want your greenhouse to last, you want to use a poly plastic that has UV inhibitors. But if you don't care if it has UV inhibitors you can use regular construction plastic that you can get at the hardware store like this:
Blue Hawk 20-ft x 100-ft Construction Film. You can get a 20x100 foot roll of 6mil thick for under $100, and they sell smaller rolls too. The construction plastic is the same thing as what you get from greenhouse supply stores, but the stuff from greenhouse supply stores have UV inhibitors (protection). That not only helps keep temperatures down inside your greenhouse, but wont break down and need to be replaced every year.
Here is the stuff I used:
Stock Clear Greenhouse Film, 6mil, it cost me a bit more especially because of shipping. But worth the extra cost. We don't have any greenhouse supply shops in the area, so I needed to have it shipped. They also have a
Double Layer greenhouse film. If your needing batten tape too, this is the cheapest I found and what I used on my greenhouse:
All Purpose Batten Strips, I got the 1,500 foot roll. For greenhouse supply's, the two places I usually go through are either
Greenhouse Megastore or
Farmtek.
You can get inline duct fans at Lowe's and Home Depot. I find the best selection and prices on them at Lowe's. The down side is they don't carry them on the shelf in the store here, but on the up side if you take a print out of the one you want, or at least give them the item and model number, they can look it up and will have it shipped to the store free.
SUNCOURT 4-in x 6-in Galvanized Duct
SUNCOURT 6-in x 6-in Galvanized Duct
SUNCOURT 6-in x 8-in Galvanized Duct
Suncourt Two Speed Professional 10 in. In-Line Duct Fan