Do you have any rare, limited edition, special Avril-related items? Perhaps a limited edition CD, rare album pressing, physical CD singles, unofficial documentary DVDs, autograph, one-of-a-kind personal autograph/photo, special plaque, an old item of Abbey Dawn, etc.?
I have a copy of the Avril Live Acoustic EP which was only available for a limited time at Target stores in 2004. It's not exactly "rare" because I believe the tracks were included on the Essential Mixes album, but in order to get the CD now you have to go on eBay or some place like that.
I also own the studded denim jacket piece from one of the early collections of Abbey Dawn, which you can no longer buy except on eBay.