I'm a firm believer in getting the most out of things you pay good money for or even find in the trash for that matter.
This Instructable shows you how to quickly & easily turn an animatronic Santa (working or not) into a Creepy Clown for Halloween.
It can be done without permanently* damaging the Santa, so you can use him for both Halloween & Christmas. 2 props for the price of 1 is my idea of getting more bang for your buck!

*Depending on the mask you use, you may have to remove Santa's hat but the hat can be re-attached with either hot glue or Velcro dots.

Step 1: What You Need

Animated Santa (working or non-working)
Clown Mask large enough to pull over the head
Clown Costume large enough to fit the Santa
Seam Ripper
Safety PIns

Step 2: Step 1

The animated Santa's legs are mounted to base, so you need to modify the clown costume so that you can put it on by pulling it over his head.
To do this, turn the costume inside out and then take the seam ripper and remove the stitching from the inside leg seam. I started at the crotch and then down each leg because it was the easiest.

Step 3: Dressing Santa

Turn the costume right side out again and pull it down over Santa's head. Pull his arms through the sleeves and then pin the leg seam back together with safety pins, starting at the crotch area and working from the back, so that the pins are less likely to show from the front. Tie or button the back up (depending on your costume), slip the mask on Santa and you are good to go.

The one I used here, did dance at one point, but naturally, I couldn't get it to do it while I tried to tape it.

He still turns his head though. ;)

Step 4: Costume Option to Consider

After removing the stitching, you can either sew on snaps or use Velcro on the seam so that the costume can be removed and replaced even faster. It also gives you a useable costume, that the wearer doesn't have to take half way off just to go to the bathroom.