No need to buy used when you can get new. Although, the most important factor is fit. Make sure you try some on. Used boots are going to be molded to fit the previous owners foot. Plus it's just nasty - snowboard boot stank and all the previous owners sweat soaked into the liners.
Lots of sales starting up now. Check out your local board shop for spring sales. If you can stretch your budget a slight bit more there are also some great boot deals on whiskeymilitia.com right now!