As a reminder, this is what my boys' room looked like before. This is the same fishy/nautical theme they've had since they were newborns.
And this is the updated baseball themed room that we did for their 5th birthday! They LOVE it!
I got the blue black out curtains (it stays light really late in Indiana) on clearance from Walmart.com. I got the posters from Posters.com (and had a 25% your whole order coupon) and the poster frames from Menards. My parents ordered the little red locker-style night stand from Amazon.com. You can't see the alarm clock too well, but it has rainbow colored numbers! I got that from Target. The little lamp is also from Target, but that has since been replaced with a Lillian Vernon baseball lamp from my husband's parents.