I agree w/
@BarleyPopBrewer in that $200 is way too much money for something not designed to do the job in the first place.
Not suggesting you should do this, but here's a pic showing how I used to exhaust steam from my garage: box fan in a window and a sort of hood/corridor/somethingorother that drew the steam in from the kettle.
Based on my experience with this, I'd think a sink would be too shallow, and not have enough airflow to do the trick.
My window exhaust fan thing worked because it forced the air to come from above and around the kettle; if the sink you propose to use is too high, too much air will come from around the sink, not enough from below it.
If you're using gas or propane, I get the idea of the exhaust fan. If you're using electric, you might consider using the Steam Slayer that BobbyM sells at Brewhardware.
I wanted a permanent exhaust fan in my garage but SWMBO was very opposed to cutting a hole in the wall to do that. I went electric, and that steam slayer is nearly magical how it captures and condenses the steam. You do need a supply of water, but for me it's a more elegant solution than cutting in an exhaust fan.
Here's a link to a post showing how I'm using it; the whole thread is worth a look-see if you have electric, and who knows, might even push you in that direction if not.
Boil kettle condenser - no overhead ventilation needed