1 year warranty, no questions asked. I sent in my original SP a month before my warranty expired because of a dead pixel (absolute lower left hand, therefor no annoyance) and they sent me a completely brand new one. A brand new one within three days of getting it shipped free from an authorized dealer and I'm on the other side of the country. Nintendo easily has the best warranty of any company I've dealt with.
NEVER BUY USED NINTENDO PRODUCTS, THE 1 YEAR WARRENTY IS BETTER THAN ANY SHITTY 3 MONTH ONE YOU GET AT RANDOM GAME STORE.