These always sell out every year!
Right now at Target.com they have their Matching Christmas Jammies available. They range in price from $10.99 – $24.99 depending on a number of factors.
If you see something you have to have I would grab it now. Then if there is a sale in the next 60 days (or 90 days if you have RedCard) you can return them and rebuy at the discounted price!