Hopefully nowhere and you will be doomed to order it online
http://search.ebay.com/search/search.dll?sofocus=bs&sbrftog=1&from=R10&satitle=jesse+mccartney+poster&sacat=-1%26catref%3DC6&sargn=-1%26saslc%3D2&sadis=200&fpos=14001&ftrt=1&ftrv=1&saprclo=&saprchi=&fsop=1%26fsoo%3D1&coaction=compare&copagenum=1&coentrypage=search&fgtp=