Who: This one is for my newest niece. I used the same fabric earlier on the party dress (project #2). I thought the two girl cousins might enjoy being twins. Or at least the four year old might. I'm not sure that the littlest one will be aware or care. :)
What: I was originally going to use the Itty Bitty Baby Dress by Made by Rae, but changed my mind. It's super adorable, but I wanted something with fixed straps. Because of this, I ended up using See Kate Sew's Easy Baby Dress Pattern. What I liked more about this option was the fixed straps which (bonus!) have elastic in them. That should still make this one easy to get on and off baby.
Although I followed Kate's tutorial, I did make one significant change. I cut the bodice pieces 1/2 inch longer, so that I could fold them under and sew the skirt bottom between the layers. Basically, I took what I learned while sewing the party dress and applied it here. It was more work, but I like this finish better. I also top-stiched around the bodice (which I don't think is listed in the tutorial).
Cost: Almost nothing. I had leftover fabric and thread on hand from the earlier dress. All I needed to buy for this project was the elastic. I paid $2.50 for a package at Joann's.