Mycomicshop.com bought mine, last year.  Their focus is American comics, because that's the prime secondary market, but they also buy manga and Shonen Jump.  Based in Texas, so you do have to ship it, but you can list on the website first to get an estimate what they'll pay.  They have some really good policies-- if it gets to them and the quality isn't what they issued the estimate for (as in they'll pay less), they contact you and give you the option to have it shipped back to you instead.  If the quality is higher, they'll just give you more money.  I had them do both with me, so I can verify that they actually follow their policies.  Good to work with, fairly quick to reply to emails, etc.  I recommend them, or at least checking to see if they'll buy yours.