They probably could port it - but it's not those 1700 bucks which are causing problems.
Converting to Wii is way more than just buying a devkit and pressing the convert button. A6/7 is an engine heavily relying on Direct x - huge parts of the core would need a complete rewrite for Wii.

And as mentioned before it's not that you can just release your game then. You need approval by Nintendo, Microsoft or whoever. This is the most difficult task.
If they really *WANT* your game, then there will be a way to get it running on Wii and/or 360... money won't be the problem then.