First off to the do it yourself person- I can understand trying to keep cost down and your idea is a creative one. Here's the problem though with just some ductwork and a duct fan. The humidity levels are different from season to season. So more ventilation is needed in summer than winter. Humidex is a controlled ventilation system meaning that in the winter time the system can be set by the homeowner to a lower exchange rate, so your heat doesn't fly out of the house unlike your option. That wouldn't be cost effective especially with the rising energy costs. Now let's talk about installation, apparently the gentleman that gave that option is good with his hands- Personally I'm not- so if I installed this unit I'd have a bigger hole than the duct most likely lol! I'm just saying :) truth. Now keep in mind that the Humidex system looks aesthetically pleasing with a proper housing- if your looking to sell your house down the road Humidex will be more appealing instead of some metal ducts sticking out of your house. We are talking about a system that ranges from $1500 to $1800 properly installed to your specs. I'd personally leave it to the experts when it comes to your house. Any question please feel free firstname.lastname@example.org.