I will vouch for the Stanley Blower.. it's great for the price. The intake is easy to make ( a bit of cutting of the plastic intake, a 4" section of pipe, cuts in one end to flange out, and good old duct tape to hold it in place.

For the exhaust, I used a rectangle to round 4" adapter, and cut the adapter down (rectangle part) to fit the rectangle exhaust, duct tape ehaust adapter on, and done!... drilled some holes in the plastic handle, hung upside down with bungie cords... and moves pleanty of air for forty bucks. Keeps my 6X6 with 1K HPS at 79-81