I will advise you to BE CAREFUL who you decide to get a replacement from. There are going to be cheap knockoffs that are going to tell you they are indeed OEM and cost a tenth of the price of others.
THERE REALLY IS TECHNOLOGY IN THE SPEN... No batteries or wizbang stuff, but there is a tech to be had, that's why not all things work as an sPen. But, you will get what you pay for if you don't buy something that is at least a few bucks, probably no less than 15 after a while and more that 25 at the beginning... So just be smart with what you do.
If you sweet talk the people at the Samsung kiosk in Best Buy, they'll give you one free. At least it worked for me last year.
I'm no hot chick, that would never work for me!