I've been making the boys pajama pants as of late because it's getting expensive for the store bought one.
Really, $12 for an outfit just to go to sleep? Enter sale fabrics from Joann's and packages for 3 for $4 T-shirts and some sew-equity and you have PJs for around $5!!!
I appliqued the "K" with scrap fabric so it would match the pants. Very easy. Iron on some interfacing to the back of the fabric, cut out your letter, attach it to the T-shirt, and then zig-zag around the border.
Needless to say, the boys LOVE having PJs with their initials on it. The only problem is when it gets handed down.