cheap inline fans question

my question is, is there a point in buying an expensive inline fan for a 3x3 or 4x4 grow tent? even with a cool tube and carbon filter to push air through, the fan is only going to be on once every hour or so...so isn't it smarter to save money buying a cheaper and weaker fan but leaving it on an extra several minutes during exhausts? does that sound right? would a fan like this work for exhausts in 3x3 or 4x4 grow tent?: http://htgsupply.com/viewproduct.asp?productID=46434
thanks for any help

those fans are shity! But they would prob work for a lil tent.