Duct Recommendations

Planning to make a duct, and i have three options:

1. a duct with only the fan on the hsf (cheapest/easiest)
2. a duct with only a fan on the side of the case, no fan on the heatsink (efficient or not?)
3. 2 fans, one on the side of the case and one on the heatsink (the fans will be close to each other; i'll also have to pay more for the extra fan hard for a poor student)

Recommendations?


Edit: 4. or how about no duct and just a 120mm fan blowing in?

1 or 4... You can use a gutted fan frame as a duct..I gutted a 92mm X 25mm to put on my SP-94 HS.. It has elliminated the dead spot marks that used to be on the HS..