It does help. Are you sure the previous owner did not put it in the trunk or bonnet? Some people even put them behind the seats. Also you may want to check the inside storage compartment. Suncoast has them for sale.
http://e-partssales.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=P&Product_Code=00004480078
No need to have the dealership install it. It's doesn't require installation, because it is meant to be removed. It just snaps into place. Are you also missing the roll bar windscreens inside the seat's head rest? You may want those to. But I prefer not to use them. They tend to make a whistling noise at high speeds. E-bay is you best place to find good prices. They even sell tinted ones(plastic wind deflector) on e-bay now.