Check
http://www.millersoap.com/soapingred.html or
http://www.millersoap.com/soaplinks.html for places you can find lye to buy. It's harder to find here in the US now because it's used in making meth so a lot of stores don't carry it anymore. My mom had to go to a bulk supplier to find it.
Just to clarify though, lye is sodium hydroxide. KOH is potassium hydroxide. Make sure you know which one you need to have.