From The Collaborative International Dictionary of English v.0.48 :
Collectible \Col*lect"i*ble\, a.
Capable of being collected.
[1913 Webster]
From WordNet (r) 3.0 (2006) :
collectible
adj 1: subject to or requiring payment especially as specified;
"a collectible bill"; "a note payable on demand"; "a
check payable to John Doe" [syn: collectible,
collectable, payable]
n 1: things considered to be worth collecting (not necessarily
valuable or antique) [syn: collectible, collectable]