A bit over your price point, but one of my favorite Merlots is Rombauer
I've seen it on sale for around $27, but delish. I have it when I want a treat. Other than that, in the under $20 price point I'm not really married to any merlots/pinots as I lean more toward cabs/blends and just tend to have fun with the Bev Mo 5 cent sales. I've never had a pinot to write home about in that price point, I've heard good things about Wallace Brook and wines from the Willamette Valley region, but haven't tried Wallace yet.
Oh forgot, Layer Cake is a nice one I've enjoyed several times and it's under $20.