Good thought, but as we're already spending a fortune to install a high cfm hood over the range (with the accompanying active makeup air system--ugh!) I'm looking for a cheaper solution.

Since it's not going in a cabinet, but rather under a cabinet, with plenty of clearance to the sides, front and back, the only concern seems to be over the oven. I'm thinking more now about adding active fan ventilation blowing back to front over the top of the oven? Maybe using something like this?