portfoliogains.com - not much value. Maybe low $xx since I can see it developed into a site dealing with stock gains.
whitesmilefast.com - It's catchy but a very narrow niche. You might want to consider turning this into an affiliate site and flipping it. Without that, I'd say $x or so.
momsfavoritecoupons.com - Develop this one. It has maybe $x reseller value at most.