I am always interested in buying collections of any size!
OPA
Tokens used for rationing during World War II
There are 30 different red tokens and 24 blue ones.
They are all vulacanized fiber (celluloid) and 16mm in size.
Blue ones read: OPA Blue Point 1 (with two different letters)
Red ones read: OPA Red Point 1 (with two different letters)
Please e-mail me if you want more than one as I may not have it.
The rarest is the red MV. The next rarest are the red MM and the blue WW, WC, WH. Then blue WU, HX and red YC, XC. The rest are fairly easy to find. Reds are a lot more common than blues.
Error OPAs are worth a little more. There is a good example at the end of this page.
Error - Stamped Twice - Off Center Red (Stamped too far off for letters to show) $10.00
Error - Off Center, Red VY $2.50
Error - Off Center, Blue YC $2.50
The following is an example of an error OPAs. The pictures were sent to me by Dan Orbeck. As you can see OPAs can be struck, by mistake, more than one time. They are also not always centered when struck.
OPA's 
